I've run games with pregen characters, but never in the blind, so to speak. To me it sounds interesting because I like improv and getting to play characters I wouldn't normally pick myself.
I do know some players who are attached to playing their characters the way they want them, either way works for me, it just depends on player preference.
I think as a primarily forever GM I tend to think that I think differently about playing characters than the players at our table.