Skill trees need to be redesigned so that all build-specific skills are optional. I should never be forced to spend a skill point on something I will never use.
Examples from Psyker trees of non-optional skills:
Volatile Substances & Caustic Agents (DoT) tree: only relevant to Heat skills, Ammo Mastery (Ranged Combat): only relevant to gun users.
There are two ways to accomplish this:
One, simply make them optional nodes like several of the other build specific skills. Kind of odd that you have some optional and some mandatory.
Two, and this is more preferable, is to make it so only 2 branches are required to unlock the main node, and better organize the branches, so players can use branch choices to specialize. For example, the Criticals tree has a branch with a melee node and a branch with a ranged node. I don't need both. Ranged tree has a whole branch for Slow/Shock/Stun/Frozen but not all Psyker builds use that.
You'd allow a lot more customization and player flexibility if you fixed up the tree design to not force players to purchase skills they won't use and don't require so much investment to get a tree's peak skill. If you really feel the need to limit how many peaks can be obtained simply make them cost more than one point to balance it out.