I like @Xaelvaen's method too, as long as the players know they are getting rewarded. imo, by having them add the advantage, they know they are getting it. Sure, a few will add it when they shouldn't, but some will forget too. And though +1 is noticeable, it won't really impact game balance.
Seriously? I've known people who roll dice individually, but picking them out of the dice bag every turn?
I don't know if anything you can say would make a difference because it sounds like those people aren't really there to play D&D, but rather to indulge a polyhedral fetish.
Should I grin and bear it? Should I try to teach them faster rolling methods?
Methinks thou dost require thine own thread....Don't get me started on my slow poke group...