Dragons being the cunning, devious creatures they are, should let a Tamer think they have succeeded in taming them. Submit to the Tamer for a time... then, boom, out of nowhere, and at the worst possible moment (Doom, anyone?) turn on their "owner". Tamable dragons? Pshaw!

But I do like the fact dragons are buffed a bit now... they were a smidgeon (a lot) too easy to kill.