As interesting as this conversation is getting (I actually enjoy finding out about past editions like you all have been discussing, game design is an interesting subject to me and seeing the process over time is fascinating), I think I've decided on the course of action.
As has been said, roles are an integral part to the game (meatshield, DPS, etc), so I'll make the following change:
Power attack will officially be reverted to PF's version, and HP will likewise be reverted. However, to try and compromise with the player, power attack is now no longer a feat that needs to be taken but a standard thing for all characters (similar to how I've allowed weapon finesse to be "standard"). Likewise, point blank shot will be given the same treatment. I do think the player will value this change, as he took a 1 level dip in fighter at level 2 specifically to get furious focus sooner, and I'll allow him to retrain that level back to bloodrager at no cost.
I will, before making this change, run through the next dungeon and make sure the bloodrager is still contributing the lion's share of the damage (after all the witch is going for a debuff-caster rather than straight damage), but still allows the magus to shine when he steps up to the plate and gets his full combo off.
Lastly, I would be ok letting him take frenzerker as written, but he has expressed distaste with certain class features other than just the potential TPK aspect.
Inspire Frenzy: hes not too keen on the whole "and now the party frenzies too", even after I said "no TPK necessary when frenzying". He suggested, with iterations on the idea provided by me, more of a X/day ability to auto-crit after landing an attack. Since we're using the 'laying waste' crit system (where critting just does maximum normal damage and adds an extra effect from a sliced cheek to lopping off an arm), I thought it would be an ok change. With the lay waste system, I believe we settled on something like +20 to the confirmation roll? I may lower it, but I'd still like thoughts on the change/ability itself.
Something something 5ft step: the cleave enhancements from frenzerker were cool in 3.5, but we noticed something in PF, namely dwarfs and dwarfs alone can take a pretty high up class feature from frenzerker as a feat at pretty low levels, the one where in the middle of a cleave you can take a 5ft step. Considering that this idea of a giant brute who just carved a bloody path through enemy after enemy was his one goal with this character (if he was more of a powergamer Im pretty sure he would take the...I think its Warhulk? Class from 3.5 that gives bonus strength every level), he felt pretty jipped. Any thoughts on this?
No Dex for you: lastly, despite it being the best backup plan to make sure a frenzerker doesnt tpk, he doesnt like that being able to balance isnt possible while frenzying. Like he understands not getting do do complex acrobatics and tumbling around the battlefield, but not being able to stand up from a grease spell made him frenzy a little irl. Again, thoughts?
Again, thank you all so much for responding to this thread. Im glad my first post got more attention than I thought it would.