Not sure what evidence you're basing that off of. An alternative explanation would be people calling for taxes on the rich to be "raised" aren't really sure what they currently are.
Of course, this is reinforced by the fact that people don't even generally understand marginal tax rates all that well, but that's secondary.
You could argue that when people say the rich should pay "more", they're talking about effective rates, but a lower marginal income tax rate would be a funny way to raise top earners' effective tax rates.