Looking at the Pathfinder version, they did adopt a lot of the WOTC restrictions on polymorph that came in late in 3e. Also, I notice they strongly limit size and type - which generally is going to get rid of the worst of the cheese.
That's true to some extent, but I don't see that it's a problem. Lots of abilities are highly campaign dependent.
For example, turning undead, a classic D&D ability, is wildly campaign dependent. So are animal companions. So are most skills.
Yes, and those are also problematic. To the point where you have have a dozen or more variant turning rules and animal companion tweaks.
I don't know if that's true. You don't get bonus knowledge ranks for living in an area. Personally, I don't know the wildlife in my area all that well, and I've lived here my whole life, got a degree in biology at a liberal arts college, and enjoy casual hiking. I think you're being too generous here (though some DMs might be that generous). When we're talking about enforcing requirements for polymorph, I think you should need some in-depth knowledge of the target, not merely having heard its name; otherwise it's not a strong enough limitation.
Mostly this was linked to the later idea of the DM using critters in the area. If you stay in one area long enough, you pretty much going to meet all the really dangerous stuff.
That is an interesting consideration. Again, I don't see a problem.
Summoning lists could probably use some more restrictions too.
True. Polymorph is never going to be easy to balance, unless you gut it. I think it's too classic to do that.
But, pre-3e polymorph is WAY weaker than the 3e version. The size limitation meant that you couldn't get too big. And, the monsters in pre-3e polymorph had such weak attacks, that any monster shape you took generally wasn't going to be any better than what you could do with spells and were most often quite a bit worse. Particularly for a minimum 7th level caster.
The problem in 3e is that the monsters got jacked up SO much in their basic attack capabilities that losing special abilities isn't that big of a deal. Again, looking at the behir, who cares that you lost that breath weapon when you have a +25 grapple check (give or take because of size and strength), improved grab and swallow whole? Or, better yet, 6 rake attacks for each successful grapple check. Attack, grab, pin, rake until dead. It's ridiculously overpowered.
In 2e or earlier, changing into a behir, which you couldn't actually do since it was too big, netted you 2d4 damage bite and six attacks (using your wizard THAC0) for a d6 each. Nice (and illegal let's not forget) but hardly any more overpowering than many other 4th level Magic-User spells.
No. The point of the knowledge check isn't to ban particularly powerful forms; it's to restrict the number of different forms a character has access to. What really makes the spell difficult is the variety of things it can do. Limiting access to that one powerful form is a different matter. Restricting access by hit dice is already in there and does that pretty well. So does restricting access to the creature's full suite of supernatural abilities until the caster gets Shapechange.
The point of the knowledge check is to cut back on casters being able to say "Hey, look, some fire elementals. What monsters in the manual are immune to fire?" Cherry-picking the ideal form for a situation. That still can happen to some extent, but is curtailed.
Note, you wouldn't gain immunities with a Polymorph spell. But, I do disagree that the problem is cherry picking for situation. The problem is that some forms are just so good that they are ridiculously overpowered. Heck, even a Troll is a nasty, nasty form. You can pump out 50+ points of damage per round with a bog standard Troll. Again, way too much damage for the spell level.
