Anything can be an excuse for annoying, stereotypical roleplaying. I doubt the halfling in one of your other stories would've acted more socially acceptable if he didn't have the letters C and N on his character sheet, they're just another thing to fall back on, and certain types such as Chaotic Stupid and Lawful Gestapo will be constant fallbacks while someone works out the intricacies of personality.
So I can think of a couple of very good reasons to toss alignment completely*, but stupid players will be stupid players regardless, so they're only a minimal one at best.
*Reasons being that it makes morality too concrete and visible (you may like that, I don't, and it'd be nicer of WOTC to give you the option to slide it into your campaign than it is for me to have to chop it out and patch some of the holes), and that I'd be hard pressed to find concensus on where the lines on alignment are drawn and exactly what means what. I'm not calling it bad, just unnecessary and a hassle to many of us.)