Guild Wars 2

Honestly I have been puzzled about these “design decisions” for the dragons/DEs as well. Take Blightghast or The Shatterer, compare it to other dragons I know from other games. As GW1 is not really comparable as all was instanced there and happens in a “contained” environment, the only other fantasy MMORPG I have played alot was WoW (let the flame fest begin!) and boy did WoW have dragons! You respected those dragons for their complicated mechanics at least.
Sure there is aggro and things were less open world in WoW, yet the boss fights are where WoW shines imho. Not everything can be reused in the DEs, but some stuff can.

Start with the way GW2 is built. No healers, no tanks, everyone should function on their own, yet DE require a group dynamic to happen. So a DE should be a group effort, but everyone needs to learn the boss tactics to survive.
I.E. A shield that reflects you 20 times attack damage on ranged when the dragon shines in bright red; or get a debuff that will cause damage when you stand still; or when the dragon is airborne only ranged does damage, on the ground only melee does;…..

I agree with an earlier post (at least for DEs). I do not want to die for someone else’s failures, but I would like to have (instanced) events for larger groups where you get punished for those.
Therefore the DE can only be changed in a way that everyone gets punished for their own failures, well, and by adding some phase-like character to the event.

That said, I agree with most things said here. What I want to add is, complexity in fights can also be achieved by adding phases to the fight where the dragon does something else than its 3 standard attacks over and over again until it dies. Zerging an enemy in 10 minutes feels not even remotely like wiping on a raid boss for 5 weeks (like I did in WoW) and then finally taking it down. I don’t think it needs to be THAT epic and rewarding, but even Diablo in D3 was more challenging (and could be done in melee without dying <gasp>).