Most race sanctioning organizations won't allow you to have them on your helmet for that exact reason.....can't be assured they'll keep your helmet on in case of a crash.
I don't see anything wrong with the D-rings, either, but my girlfriend has a hell of a time threading the strap through the rings. Deal with her is HER helmets have buckles.
And we all KNOW we don't ever ride without helmets, don't we???