I dislike the locks as well. I hate the way they look, and while the chances of spontaneous activation may be miniscule, it could happen. I'd rather not add another point of failure to the mechanism if I don't have to. And I don't have to. I'll just buy used S&W revolvers made before the damn things were added (just picked up an early production Model 29, complete with the "coke bottle" grips.)
But my chief objection to the internal locks is that some people may rely too heavily on them for safety. An external lock, such as all gunmakers provide these days, is fine. You can leave it off, or put it on, but if it is put on, you can tell at a glance that the lock has been applied. Not so with the internal lock. You can't tell just by looking, and a person may think the thing is locked when it isn't, and assume the gun is now "safe." This may actually increase the likelihood of a negligent discharge, especially if the weapon is left unsecured by someone trusting a lock he or she only thinks has been engaged.