I'm planning to provide some new feats to help boost AC. But even so, the only classes that will really rely on AC to help them survive will be fighter, paladin, and cleric (and probably druid.) Wizards and sorcerers will have to rely on their allies and/or mobility, monks will rely on mobility, barbarians will rely on their hit points and DR, and rogues, bards to some extent, and rangers will rely on their hide checks (and also, in the case of rogues, on not staying in the fight after the first hit)Unless you can wear full plate, and more than half the classes can't, your AC will be 30 or less unless you're shapeshifting somehow. (10+10 for a +5 breastplate +3 Dex is 26 for a barbarian, 10+5 Class +10 Wis +5 Dex is 30 for a tank-monk, 10+9 for a +5 chain shirt +10 Dex is 29 for a rogue)
There are a number of decent nerfs that casters can do with a decent chance of success. Nothing battle-winning, but Shaken or Sickened are some pretty decent debuffs.This means, if you're getting full-attacked by a monster, you're going to get hit almost every time at higher levels. So how do you kill a monster? You have to nerf it somehow before you charge in.
A 29 instead of a 34 isn't all that much worse. And there might not be a Shock Trooper, but there will be powerful feats to replace them.Now you're going to charge at a monster who was CR'ed with the intent of facing PCs capable of casting miracle, flesh to stone, and destruction, but with a 29 in two stats and your defensive spells killed, no Shock Trooper, no Heedless Charge, etc.
How are all those things poorly designed? Most of them are relatively straightforward to counter, and the few exceptions I plan to make melee classes more powerful against. Not that grappling a Tarrasque will ever become a viable strategy, but against dragons it'll be quite feasible.You know why non-Core exists? Because the MM is poorly designed. Because regeneration, DR, level-draining, rending, grappling, swallowing hole, and other things, are poorly designed. Because you're going to fight monsters as superhumans, when you need to be a monster to fight a monster.
The problem is that "optimization" seems to help out the casters more than anyone else, and that makes it no fun for non-casters who can't use non-Core.If you want to kill the tarrasque with damage, you're doing it wrong. If you want to kill a dragon with damage, you're doing it wrong. Monsters are designed to be challenging to sub-optimized, equal to optimized, and devastating to unoptimized
The monsters face the exact same limits; they just don't tend to use the same effects as often. (That said, the condition levels change will be a relief when fighting a basilisk.)So by nerfing damage, by nerfing debuffs, by nerfing stats themselves without improving AC or weakening enemies, you're basically setting up higher level games to be completely unbalanced and challenging, requiring immense amounts of optimization from the players who can't optimize because there are limits on their power, when there are no such limits on monsters.
But overall, your post seems to be working on the assumption that what's been done so far is a representative sample of boosts and nerfs, while it's not (it has far more nerfs than boosts as compared to the completed version.)