I know a lot of players who like the feel of moving air on their pant legs, but I like my sound up where I can hear it. Back when I had a Kustom 3x15 it wasn't much of an issue...but I've been using a single 4x10 for the past 10+ years. Early on, I wasn't comfortable with the low cabinet...and then I read something (I believe it was Mike Watt) talking about how he always lifted his cabinet. I tried this once and have been doing it ever since. First off, you can turn your amp down since it's closer to your ears...second, it puts my head at an easily visible level for tweaking without bending and for checking my rack tuner.
But there's one other BIG advantage. Most of the stages I play on are hollow, and amplify the boomy super low end of the amp (think about the airspace in that box) if the cabinet is placed directly on the stage. Since each stage is different, it adds a whole new variable to each room you play...which if you want to retain control over your own sound is difficult to deal with. Less feedback, better sound, more control...all good things.