Defiance is a crutch at the moment as far making new dungeon bosses. Defiance is the reason why a condition builds does not do the same damage it does against monsters without it. When I take my rabid engineer into a dungeon I kill trash mobs just as fast as I do with any of my berserker geared toons, when I get a boss or a champ though I notice the difference. The conditions that I am spreading do not last as long as they normally do thus making the fight last longer and making the encounter harder on everyone. This sucks, because I like playing my rabid engineer dungeons every once in awhile because it is different play style.
Guild Wars 2 broke the holy trinity which made me extremely happy. However, instead of it being Damage, Support, and Control there is not much in the ways of Control at the moment. Damage is something that everyone is going to do regardless of build and or gear how much though can affect your dungeon experience. Longer encounters equal more opportunity for someone to mess up. This why Berserker gear is so dominate at the moment. Any condition a berserker applies is a minor bonus.
Normally when I do a dungeon I bring my berserker geared guardian with its berserker hammer + magi mace and shield combo being 10/25/0/30/5 build doing my best to maximize damage without neglecting trying to support my group mates. Support in this game from I have experienced breaks down into condition removal, group wide boons or banners, and healing someone who got low just enough to keep them going until their heal skill comes off cool down. Cleric’s with Magi gear mixed in to me doesn’t make any sense because you can’t keep the group alive by yourself and game wasn’t designed with that in mind. Only way I see + healing gear working would be to make it a fourth stat PvE wise =/.
Control in this game doesn’t exist outside of trash mobs. Why bring a hammer warrior when he isn’t going to the same damage a great sword or axe + mace warrior will. You have to break through the defiance stacks in order to control the boss. I’m not saying that we should be able to chain stun, fear, or knockback/down a boss, but that’s where boons like stability come into play. I would like to see more bosses with this design in mind.
Bunker busting should also be a group role in this game. Classes like necromancers, Mesmers, thieves, and to lesser extent guardians and engineers all have traits/skills that remove boons. If bosses in the future where designed to cast stability on themselves and go on a rampage until they are hit by a crowd control effect might a bit more depth into the game. You would need someone to bunker bust so the soldier geared warrior with a hammer can go in and stop it. You could have a boss that goes on an absolute tear that people will have to blind, block, and absorb its damage because dodging will not be enough. The last boss I mention would have great sustain damage, but wouldn’t hit to hard. You can make bosses immune to blinds, immune to CC, or heck even immune to damage. You could even make a boss who requires you pick up environmental weapons to damage it. Bosses could even remove their own conditions like alpha does!
In conclusion I feel that defiance right now is more of crutch hindering the development to making new and interesting boss encounters.