Noise alerts should be limited to imminent threats or severe safety warnings (fast approaching a slower vehicle in the same lane, seatbelt not fastened, etc) but not for activity that a) may actually be totally legal, and b) may cause panicked, reflexive actions, or c) may cause confusion for the driver.

I could also see it get really annoying for those of us without functioning cruise control trying to go the speed limit consistently, depending how close to the speed limit is started to beep.