Well, you better get used to it. You shall be playig it over and over and over again, all the way till Developers have decided to the whole Campaign thing is going to be available to skip over to focus entirely on Challenges alone perhaps, if that what is one desire.

But Tank and Crimson Wanderer is part of the Campaign, so one needs to play just as everything else as in Campaugn.

And the Difficulty is what the difficulty is. I play the entire Campaign on Difficulty +3-+5. Never lower. I´m sure there are those who is even going higher too.

If you are having trouble playing ANY Mission within the Campaign, and needs to go lower then even +3, I suggest you should, as they call it, git gud.

Having gone through the entire campaign ( and side missions ) a grand total now of about a dozen times ( ive deleted several characters and still have 6 remaining active all that are campaign completed. I hate doing the entire campaign each and every freaking time now. Especially the Knight missions. Once we have completed the entire campaign and side missions to get the Morality maxed we should be able to skip that entire headache and simply pick the morality choices to get our desired outcome from them. I dont play this game for the campaign anymore ( that stopped at about the 3rd runthrough ) I refused to play the season of the warp surge because i hated running the campaign and the knight missions especially. I play now just for general and intel missions and for Co-Op with buddies and new players to help them level up and learn the game dynamics. The storyline is irrelevant to me at this point. I utterly agree with Hack on this. Once we are fully done with the campaign and its side missions for morality choices let us have the option of skipping it for the next character ( still need to pick the morality choices though ) 

Totally agree with the OP.  Boring as hell and with no resemblance to the play style of your character.

Actually, the Crimson Wanderer missions are done very quickly. The key is not to shoot - you just walk over the mobs. The walker is so massive, it can squash everything except bosses and other large machines. So you basically just walk to your objective, squashing hordes of mobs beneath your feet, then you snipe the boss with your cannon (which usually takes just a couple of hits) and you're done. The mission takes 2-3 minutes.

The problem with these missions is not their pace - it's the lack of any rewards or XP (apart from the mission completion XP). Especially now with seasonal characters when named bosses spawn in a CW mission - it's a complete waste, as they will not drop anything.