I might agree with the dragons needing a few more "attacks" to vary the fights up a bit and make them feel more like... dragons. That said, I did notice the same thing a previous poster did with Teqautl, in that at one point (not sure when) he changed his attacks up a bit and started throwing out some serious damage in the 0-1200 range I believe and just wiping people out. I assume this is thanks to more people joining the fight (which if I remember correctly, A-net stated the more people you have there, the harder the fight gets, not just in terms of HP pool but with new mechanics being added based on people).
And for a wicked fight, just go do the Risen Priest of Balthazzar fight. I've seen more full wipes and fails there than any other boss in game.