Jackinthegreen
Explorer
BAB isn't just for attacking. It's also added onto Sense Motive checks against feints in combat, for example. In effect, it's a measure of combat experience. You're telling me a wizard is -worse- than a commoner on those grounds? I don't think so.
Since you mentioned full casters with no distinction to arcane or divine, let's look at divine ones too. Cleric? Divine Power. Even if you make his class 0 BAB, it's only a spell away to get the same as a Fighter.
I don't agree with changing BAB for classes, including full casters. Everyone will have some form of combat experience which grows as they level. If you want to balance things better, BAB is not a place to do it.
Since you mentioned full casters with no distinction to arcane or divine, let's look at divine ones too. Cleric? Divine Power. Even if you make his class 0 BAB, it's only a spell away to get the same as a Fighter.
I don't agree with changing BAB for classes, including full casters. Everyone will have some form of combat experience which grows as they level. If you want to balance things better, BAB is not a place to do it.