I'm fine with them as long as they're suitably difficult to kill. Dragon Age did this fairly well, where they're the toughest things you'll have to fight, and you feel like you need several people with their own complex strategies just to take one of them down. Even with high quality weapons, armor, gear, spells, potions, and stats, they're still bitches and a half to take down. If you can saunter up to a proper sized dragon by yourself and carve it up, it feels like an overly large, bitey deer to me--because if just one person can take them down, how is it that they aren't habitually hunted? It really negates the point of them if you can just mosey on up to them and carve them open.