A little flair, but no unsightly bulge here:
Shellac ensures curling tape isn't a problem, whether you wrap top-to-bottom or bottom-to-top. In any case, if you regularly exploit all the real estate of a drop bar, at some point you'll be putting your hands on an area where the overlap can become curled up over time by contact.
As for the question of the benefit of taping top-to-bottom: what's the benefit of taping bottom-to-top? This tape direction argument never seems to get old, does it?
DD