Etiquette break

On the clichéd 'have a nice day'...

It makes me crazy when someone musters a wan smile and coos "Have a nice day". Even worse is the more contempo version of that, namely "Have a good one." I'm sure the sentiment is sincere, but I just find those utterances so lame and banal that they make me want to throw things. Who gave these cretins the right to assume that "a nice day" would be the best thing for me? I mean, a 24-hour session of smelling pansies, waving at babies, and picking up litter? That would be utter hell on a cracker, and I would suffocate from the deadening boredom of it all. Even if they're just offering their kind hope that things will work out my way, it seems so hocus-pocusy and unreal, especially coming from low-level shop clerks. Is their wishing I'll have "a good one" supposed to automatically bring it on? Are they holding a rabbit's foot and some prayer beads under the desk when they so optimistically say that? Why not keep their goodtime voodoo hijinks to themselves and just THINK "I hope he has a nice day"?