Then why don't just pick another gaming system? Plenty out there, and saves you the work from remaking D&D from scratch.
You tell me. You're in this thread, after all. Why are you discussing this instead of just playing another system?
Because maneuvers are weaker than spells. And again, a warblade whitout Int bonus is basically losing several of his class abilities, as a +0 bonus may as well not be there.
So the mechanic exists to balance casters and noncasters? Boy, it's sure doing a great job.
Watching out for corners is one of the finer points of good design. Much of D&D's problems are precisely because those "corners" weren't taken in acount and TO will use and abuse every unpolished corner they can find. So why take the risk that someone finds some loophole that allows them to cast the spell once you remove the ability prerequisites?
Uh, because that's what I want? I don't want someone to have to have a certain Strength to take Power Attack, and I don't want someone to have to have a certain Intelligence to cast Scorching Ray. The ability score prerequisite means that you're being denied abilities which are level-appropriate if you don't meet those standards, and it only works in those corner cases. If it's the fixed 3.5, you're being fucked out of the ability to perform adequately. If it's normal 3.5, it does...pretty much nothing.
See, now that is actual bad design. The idea of "Casters are already strong, so it's allright to make them stronger" has possibly been more damaging to 3rd edition than anything else. Just because something is broken, is no valid excuse at all to make it even more broken.
You keep missing the point here.
1) In the case of an overall rebalance, you can get away with this because
the net result is a nerf to casters or a buff to noncasters or both. If I add two to a number and at the same time subtract five, the net result is a decrease in the value of the number.
2) If that metaphor were extended to this case, I would be adding two and subtracting approximately eleven thousand. It's seriously not a big deal to do this without touching noncasters because, as you pointed out, the mechanic only applies in corner cases. It doesn't work even then. It would be like me expanding the cleric's skill list to include Use Rope. Yes, it's a buff to a caster, but it's not going to make the class explode with power. No one who wouldn't play a cleric before will play a cleric now because oh fuck yes, Use Rope. And if giving nice things to casters makes you that uncomfortable, get rid of ability score prerequisites in general (because the mechanic is universally bad). That's honestly more of a buff to noncasters, and it bears repeating that
balancing the two is what I've been advocating since the beginning.