I don't know exactly why, though they are adamant it's a fish welfare issue, but an increasing number of big carp fisheries are banning the use of barbless hooks. If you are going to see mouth damage, it's likely to be on match type commercials where barbed hooks are banned. What exactly causes such horrendous damage is open to debate. No doubt some will pounce on overly heavy gear, others will mention "skull dragging". I'm more concerned with the seeming inability of so many anglers to unhook fish quickly and efficiently, even with barbless hooks. The fact that it would seem that so many anglers don't appear to carry disgorgers or forceps is concerning. Unhooking shouldn't be a problem for any competent, and suitably equipped, angler, regardless of whether barbed or barbless hooks are used. Sadly, it seems that too large a number of anglers can't grasp the concept of a hook having to come out the way it went in. Lipless roach and rudd on barbless only venues are testament to the fact that simply pulling is an all too common unhooking technique.
I generally use microbarbs unless rules dictate otherwise. I have no particular problem using barbless. However, the vast majority of my angling is on the upper reaches of rivers in trout and grayling territory. I have tried barbless hooks on such water, but losses are ridiculously high. Whilst I make no claims to angling greatness, I'm not convinced that the best anglers would do significantly better. A fairly high percentage of microbarbed hooks come out in the net with trout and grayling. The only way of slightly decreasing the losses on barbless hooks is to use a pattern with a much longer point. I dread to think how long the point would need to be to match the performance of a barbed hook.