i can understand the argument that spellcasters are basically an auto-attack npc for most fights. yes they have a couple of per-encounter abilities.. especially as a watcher.. but still.. most of the spells they have access to cant be used in most encounters.. that is unless you want to waste all of your camping supplies early dungeon.
the above being said.. thats part of life as a spellcaster in a pen and paper system. and im actually ok with them bringing that to POE. back in the day, that IS what baldurs gate and those kind of games were really trying to do.. and IMO, the experience in this game feels very close to a pen and paper experience instead of a hack and slash video game.
also, there is nothing stopping you from limiting the lore skill to your spellcasters and using scrolls. now you have spells coming out of your ears that you can use in combat. also, there are magic items in the game that give you spells that you can use per encounter. again, there is nothing stopping you from limiting those kind of items to your spellcasters. now you have even more spells.
yes, it sucks you cant have the most optimal buffs every fight, but there are workarounds even here. craft potions and put a few points in survival. and with the stronghold bringing in income which i hear is no joke, especially late game.. now your characters have buffs... if not every fight.. most of them.
so in the end, is it really THAT BAD? i would argue no.
just my 2 cents