The thing is it's not mathematically incorrect (perhaps the word I'm looking for is unprofitable?) to raise/get-it-in on the flop, but it's not the best option. We don't get anything more out of the air part of his range and it's possible we make him fold the made hands we're crushing (say he's 3betting some low AXs type hands or KQ although I think in today's games a lot of players are checking back flop with those hands).