The only point I can agree with is that the skills that give you AP are too strong. But that doesn't mean "the rogue is OP" any character can learn any skill if you put a point to its school, so you can have the same amount of AP on any "class". Problem there is, having to find those books, spending the point, and learning them with all your toons, which, of course, you don't want to do.
Otherwise, I have played Act I now 5 times, and I have not encountered any of your problems.
- I could buy all the skillbooks for all 4 characters, never needed to steal.
- I actually quite like the summoner, even though it needs at least 1 other school of magic or skillset to really be useful. But clever positioning and using different grounds to summon stuff on works really well. You just have to know your enemies.
- I also made a fun run with sub-optimal heroes, all having the Zombie talent and not being OP as hell, and I finished without any difficulty, so I would really not say you "will be obliged to play" some way even on higher difficulties. If the difficulty will be around the same as in D:OS, I am not afraid for sure.
- I haven't had a problem with my melee characters, if you position them right and use magic to counter effects when necessary, you won't get burnt/poisoned/shocked to death or stunned all the time.
