I don't understand the need to balance out roles per power source and balance out attacks per ability score.
Because some people always got tired of Charisma being a dump stat. Does it "make sense" to use Charisma? Depends entirely on where your "realism" dial is set... and we've seen in multiple threads, KarinsDad, that your dial is set much closer to earlier editions of the game. Realistic
enough in certain rules and places that matter most to you for whatever reason... despite the fact that they still aren't actually "realistic" as an absolute.
For many people, though... the ones who like the 4E game... the dial is set in a wildly different direction, where the usability of interesting game rules matter more than trying to recreate a "realism" that the game itself already has baked in (rather than being willing to create their own realism by justification as you put it.)
But you know what's the best part of D&D (in all editions)? It's all fudgeable. In every game, you could (if you were so inclined) houserule the game to remove any offending parts you didn't like, and the game still works. So if you didn't like using CHA as an attack stat... you could easily change a Bard's attack stat to INT or DEX and cause no real problems. Would entail a little bit of work? Sure. But if the game is otherwise fun to play... running D&D entails a little bit of work anyway, so why not houserule?
After all... if (in another example) you like the 4E game but just can't get past the use of the word "Bloodied"... it's no big deal to change it to something more palatable. And it won't effect the game at all.