I agree that higher marginal rates on the "middle" would likely increase revenue, it might also send us into recession which would counter that. If done judiciously, it could work. You can see how Denmark does it, they have a high marginal tax rate on fairly modest income, but just raising the top marginal rate on higher incomes doesn't seem to raise much if any additional revenue.
I think Republicans COULD have inserted at higher rate of say 45% on income above ~a million for imagery sake. Then they could claim to have raised taxes on the "wealthy". I know the notion was kicked about briefly.