It seems to me that what defines a class is the top row eg blitz, aura, ability & iconic.
The feats below that are bound to columns should be unbound imho. A choice of 18 perks to be selected across 6 slots entirely how you want them to be, namely, increase the variety of subclasses within the class itself.
Could this lead to egregious balance issues? Potentially but I’m not seeing any particular combination in the Ogryn feats that when combined in a unbound way would be. In its current state I am seeing a lot of feats I simply will never use because they are hard choice locked behind a better perk even if they would be complimentary for my playstyle.
With the RNG nature of the Weapon system it would be nice to be able to have control over your character and have, by comparison, significantly greater scope to tailor yourself to any given weapon/loadout