Actually, I think that is a strength of the class design, not a weakness. I can play a wizard who just has a talent for magic, but isn't a genius. He'll know less spells, the spells he does know will be pulled from a more limited list (save DC 9 for fireball would make it much less useful, as an example) but it CAN be done. Will most people do it. Probably not, there are still a good number of reasons to have at least a decent intelligence. But I really like the idea that not all wizards have to be super geniuses (or super charismatic sorcerers, etc). Why should a cleric have to have a high wisdom to gain blessings from a higher power? Are you still incentivized to have a good wisdom? Yes. Necessary. No. It allows for greater "character" customization, not just "class" customization. (Tangentially, I always felt it would be more appropriate for the cleric to use charisma than wisdom anyways. I have a nice rant prepared, but I don't want to derail the thread or come across like those with other feelings are having badwrongfun).
Pemerton, at least in the sake of combat I know that this is strictly not true. Technique is gained as a result of training, not just physical fitness. As is a proper mindset (this could be lumped in with technique, arguably). Those things make a HUGE difference.