Except for a few bad days, I generally don't wait long for my checked luggage. It's sometimes already there by the time I make it to the claim area. Finding overhead space can be a hassle and I much prefer boarding and unboarding without dragging a ton of stuff. And carry-on obviously limits the items you can bring along on a plane.

Your arguments are perfectly valid for some, but this is isn't a case of "this method is obviously right".