The existing formular is far more complicated than that. What you've suggested is to throw away AC, AA's, and other things and instead just use level.
These aren't simple formulas and as Trevius already said, nothing is going to change unless you're able to propose something which makes significant advances towards being live-like. You'd also have to prove this, and that it scales properly across all levels.
If you're prepared to parse and analyse a million or so fights at various levels with various AC values.. That's probably the level of effort you're looking at. (I don't think I'm exaggerating too much
)