What do you mean, casters are ruined? Casters rock. Particularly Blood Mages.
Blood mages are an exception that basically removes the 2nd biggest problem of caster. The biggest problem is acc. Now, if you are high level enought to land your fireballs with 80% than maaaybe the caster is a tolerable member but not great. But for me the caster is looking at 20% acc on enemies that matter, so his 2 casts are worth about 0... even with Weycs wand that turns misses into grazes.
But wizards are ruined: terrible acc, 2+1 casts, long casts, no dmg afterwards, wet tissue, have to pick and chose spells to match books like an autistic moron. They are dead weight.
As Example, last fight for me against Nemnoks crew. Party is level 11, mind you.
I cant replace Eder with a wizard, the wiz will get fucked up even before this measly 2 casts of protections run out.
Cant replace Maia, ranger, since she has about 30+ acc on a wiz. And will deliver dmg long and hard, and has prone on graze with arbalests.
Cant replace Serafen, cipher, cause he is cruicial to turn low-will nasties who the wiz just cant kill even remotely with his biggest nukes. 2 eoten. Nice Ringleader at the start of fight controls a bottleneck that a wiz just cant control in absolutely no way.
Cant replace the priest cause he has acc bonues for whole party. Some heals too and emergency ressurect.
Whats left is the assassin who is a better stealth nuker with items and a backstabber with axes later. Because of the +25 assass acc bonus and items bonus and all the hit to crits.
So a wizard is gutter trash in this party.
And I have a feeling in just about any other party a wizard can be replaced by a better class.