Let me start off by saying I love this game, so take everything that I say with that in mind.
The problem has very little to do with the “trinity” system, and everything to do with the content not matching the class design, and general lack of difficulty. The classes are designed quite well for the most part, with each class being able to fulfill every roll in some respect. However, the tasks that the game asks us to perform don’t really require a particularly nuanced or multi-faceted approach. With the exception of “stop skritt from stealing X” events, crowd control is almost completely unnecessary in PvE. The “support” role ends up being just stacking buffs, and as numerous people have said, at the end of the day damage takes the field. What we need is encounters where control of the battlefield is ABSOLUTELY necessary, and where the wrong buffs (or poorly timed ones) result in failure. And healing becomes irrelevant because no matter how many points you put into it, you can never be particularly effective compared to the damage done by powerful enemies, and more importantly, that damage is incredibly easy to avoid just by being on your toes as a player. (i.e. You don’t need to heal damage you don’t take) However, I maintain that what we really need back is the wipe. It’s SO difficult to fail in Guild Wars 2. Even if you’re playing with inexperienced, poorly equipped people, a dungeon encounter can be kittened up numerous times until you get the hang of it, because you respawn 8 feet from where you just died with an imperceptible amount of armor damage. And don’t even get me started at the mindlessness of the personal story encounters. Sure, you can fail at Tequatl or jungle worm, but there are no consequences. You say “oh well, there went 20 minutes,” and go about your way. Moreover, the solution to every problem is overwhelming force, because the imposed challenge is always time. The epic scale of events is cool, so I’m not saying get rid of all the people, just find a way to mitigate our numbers, so that the solution isn’t always “need more people at red!!” That for me has always been the worst part of this game. Combat in PvE just isn’t terribly interesting because it’s so easy. It’s nice to be on the edge of your seat every once in a while. Now there are ways to manufacture a challenge to make use of your non-zerker gear, like soloing fractals. But this often ends up just being LONGER, not MORE DIFFICULT, and the rewards are less, not more. So yes, you don’t need zerker gear, but if you don’t have it, you’re basically just making killing monsters more time-consuming for yourself with no payoff.