Maybe it's just been my choice of weapons (though I think the only thing I haven't used much of so far are 2h assassin melee and the needler/Exitus, really), but I can always find a use for almost all of my weapon abilities on all of my characters--especially in a group.

Skills I might normally forego to do something else, suddenly become useful as I use my enhanced mobility to hop about and drop debuffs or area denial (depending on loadout). The knockdown/stun barrage from the heavy bolter becomes quite useful in a party, and I'd imagine that, were I to resume carrying my AGL, I'd get as much or more use out of the stun munitions than I do as is.

I like the system as it is now, because I can build my skills around the weapons I am going to use (usually one overheating heavy weapon and one ammo-using rifle).

Some interesting ideas.

- Balancing issues aside, because clearly there is still much work to be done - 

I think it was one of the early 2016 interviews where they discussed why they wanted to have purely weapon bound abilities rather than character bound. From my recollection it was because they felt it was a better fit into the lore etc. Although obviously you can also make the argument that inquisitors still learn skills and the rule books even allow for such things. 

The points you put forward probably would be a fair system to use in place of the current. There is certainly something to be said for customization and the current system does tend to limit the usable skills rather than encourage diversity. Got some ideas of my own -  based on making the best of the current system.  

Won't ramble into too much detail because i'll be able to make the points a little clearer verbally in the weekend's vid on the state of gameplay - But in brief I think there is work to be done with the weapon skill system by shifting away from giving weapons abilities that are single purpose and spammable. Instead moving toward having at least the basics of a rotation system with a narrower focus of specialty (Bolter is just too versatile for eg, it's not jack of all trades, it's master of all trades!)

As a somewhat basic eg. Ability X lowering armor and ability Y doing bonus damage to enemies under the effect of ability X. While simple it's something that's been used for years to encourages abilities to be used and not sit there idle on the toolbar. Of course you still need to save some space for the odd situational for eg.  Heck even MOBA's have basic rotataions you do if you don't want to fail miserably.

For me at least this would be a vast improvement over the 3 spammable abilities which end up as turning to 1 after skills and gear are factored in. There would of course be a bit of a downside though, it would mean that if Weapon X makes Weapon Y do more damage, builds will literally always focus on Weapon Y - reducing diversity.. One of the very few advantages to the current system is that you can at least choose which of a weapons abilities you want to "bump" via skills and gear. Not that it does much for the gameplay though.

Rapid fire and full auto are two different things though, as you see from the wide cone you're not actually aiming really, you're just loosing a flurry of ammunition to keep heads down. A far cry from the measured bang bang bang of a rapid acquire-and-engage drill.

I'd have to admit it's splitting hairs, but a DMR =/= a sniper rifle. Most DMRs are chambered in intermediate cartridges, and have lower range but lower recoil. A proper sniper rifle is tuned a lot more, and is generally not built for that sustained rate of fire--you need cold bore shots for the distances sniper rifles are built to engage at, and rapid fire cranks that bore temp up fast (very fast). Currently most platforms are bolt action for issue sniper rifles, generally because we're expected to chamber military/LEO in .338 LPM or .300 WM (there are some, like the Omen, that eat the latter and are repeaters, but .300 WM heats that bore up fast)--up until relatively recently you could only get the kind of consistent lockup out of a boltgun, not a semi-auto. That would lead into a much longer and more technical word vomit, so for the sake of not derailing too hard I'll leave this point at that and move on.

As for the Mozzie drill, I wasn't so much saying that it's not something to consider as a mechanic, but pointing out that it's multiple taps before the final bang. With some of the fluff that's been written, operatives do in fact still hold onto engagement methods created in modern times (in fact though it's not called such IIRC one of the stories actually has a Throne agent using a Mozambique drill), so I wouldn't be surprised by (or against) the use.

I think I mentioned previously that I can get a bit pedantic over things in that field because it's my realm of specialization; so a lot of what I'm writing has no bearing on the fluff whatsoever (Brits writing guns!), it's just clearing up things that get under my skin because they're never properly represented or researched.

I won't even begin on shotguns, because the amount of rage gaming has caused with those has looped the complete circuit and returned me to "don't even care anymore".

I'm not sure that the solution is to, necessarily, bin the system as it is. I'd love to have a couple active skills, but as it stands I like the freedom to choose to fill a role (which is why I generally carry two weapon sets that fill different roles). As discussed prior, the plasma weapons are the go-to MEQ killers (in this case, elitebane). The bolter is a jack of all trades, master of none. You'll notice it doesn't have the sheer balls out aimed shot damage of the better sniper rifles, nor does it have the autofire saturation of the heavy bolter. It is a generalist weapon that does a lil bit of this and a lil bit of that.

As it stands, some of the weapon skills need to be shifted around and looked at, you are right. Full auto on a sniper rifle, for example. Lolwtfbbq? Or Eviscerate, which acts like a secondary skill, being the primary chain weapon skill instead of a cleave. Shield block, which has a five second cooldown (which is high even for an MMO active cooldown mitigation). Once more, full auto on a sniper rifle... We could stand to have a pool of active skills, yes. But I personally like the concept (I'm a bit biased as I pitched that very concept a few years ago elsewhere) and in practice it goes rather well outside of the obvious "early build growing pains".

Personally it feels like divorcing from the D&D 3e Syndrome, wherein a game is built around optimal active abilities chosen from a pool full of newbie traps, with far too little focus on the character itself and far too much focus on the kinds of gear made for your class. And that's a good thing, because 3/3.5e D&D was god awful and raised an entire generation of gamers (both digital and tabletop) that answer "what kind of character do you play" with "a barbarian with +5 Demonbane axes wearing mythril chainmail". There's no character to those characters, just the numbers. That killed MMOs, where once upon a time they were active roleplaying games and then through the era of WoW became roll-playing games where your stats were what mattered. From a designer's standpoint, that's appalling. You can't call something a roleplaying game if there's no role to play--that's just blasphemy. And then, grognards started to yank things away from that trap (a little too far with 5e, IMO) so that the character was again the focus. And that was a good thing.

I think, in general, that some focus should be put into making some of the passive skills more balanced with each other--in a few levels I added something like +25% DoT damage to the already steep DoT damage I had, but my +DR tree gave me a total of +9% for almost twice the skill point cost; and it's far harder to get good +DR/+Deflect gear than +DoT damage/+DoT duration gear. That, coupled with the aforementioned rethinking of the skills applied to weapons, may actually prove more beneficial in the long run while keeping in line with the current stated intention that they want players to think things out (including what they launch into a mission with).

As vaguely related input... I'd like to note that I find the shift to Fleshbane for the chainsword to be weird, to me. The fluff always was up front about those teeth being there to chew through armor and flesh equally well, so the shift to them being "bad" against armor in crunch struck me as weird--that was where the low-tech melee weapons were, then chainswords to be okay against both, then power weapons to be the "pinnacle" of your anti-armor melee.

Unrelated: Mozambique drill is two to three rounds center of mass in the heart region and one shot in the T (where the eyes represent the horizontal line and the nose the vertical), not one and one, and it's more of a method to bypass body armor (the third shot being a just in case) than to "stack extra damage". Placement is key, because the forehead is dense enough that it's actually damn hard for pistol caliber shots to penetrate it. There's a very high chance it'll deflect and while any lead hitting something hurts, it's a follow up to disrupt brain activity totally.