Yeah, that sounds familiar - iirc it adjusts AC to compensate. (That had an unexpected side-effect too, which I didn’t realise until months later: it caused Greater Restoration to undo the shift, because the effects were linked!)
I think saying that I was “biased against them” is a bit of a stretch though, since I added code to merge equipped items onto shifted forms, added code to improve saves to match the Primaries of the shifted form if they were better than the caster’s (i.e. the Animal forms get Reflex Primary on top of the Fort Primary that they and Druid’s share) without corresponding REDUCTIONS to any Secondaries the forms have, etc. And, oh yeah, give them the BAB of the new form.
It absolutely IS fair to say that someone at BW had a hard-on for the class though, because the balance is a joke. When the baseline is THAT bad, there isn’t much you can even do to try and fix it without ending up as a nerf in ONE regard or another.
There’s no question, at all, that Monk1/Shifter is broken AF. And if you’re balancing for a PW (and especially so for PVP), you need to do something about that. It doesn’t matter how cut a mechanic you, or I, or anybody else thinks it is or isn’t: it’s just plain broken.
But EVERYTHING to do polymorphing is broken in NWN, in every way, because the engine flat out just isn’t built for it and handles it terribly. Shifter should never have been added in the first place if they weren’t going to fix at least SOME of those bugs as part of it.
What I arguably should have done though is add a switch for it, because my position is that players are free to do what they like in SP: after all, if you can godmode your char then nothing else really matters. But TBH I was already so sick of the half-assed design and implementation of the class, and all the stupid bugs in it (like getting half your spellbook wiped out whenever you shift) that I didn’t want to spend any more time on it than I already had.
Ultimately, the best way to deal with the bad design and implementation of the class is to simply not have Shapes that are better across the board than a PC build of the archetype is. That takes a LOT of playtesting though, and like I say just isn’t relevant to SP anyway. It also only benefits the tiny fraction of players who are interested in the class, so with literally hundreds of buggy and badly-balanced spells to deal with that affect every player and every playthrough, I just gave it up as a dead loss and returned to the pieces that were a better return on my time.