Well, with 'dead' cues (Uni-Loc joints come to mind), you don't know the exact spot you're striking. Yes you can see it with your eyes, but you don't have the response in your hands that says "yep, that was a nice stroke" that many people favor in customs. Bumperless cues enhance all of the resonance because there is no rubber to dull the vibrations, as you mentioned. (Brunswick referred to bumpers as 'noise subduers' - I love that name)
Bumperless cues don't pocket balls for you (I'm first in line to get one of those), but they maximize how much control you have over your game.
+1
As for bumperless cues being more fragile, I really can't agree with that unless you're a careless type person.
My cue looks just as good now as when i got it.
I leave cue abuse to guys like Earl Strickland...