I think a big problem is, that there is no real challenging dungeon content. As they said before, you can do the most dungeons, with a lot of different build. Ofc with zerk it works faster, as we all know. The only place where full zerk doens´t work all the time, are fractals, because there are some bosses who just need time, not pure dmg. But these are just are few and u can do them with full zerk groups. So if we had places like the underworld in Gw1, you would need atleast a tank and so on.
The same thing in the open world. Things are too easy and you can do them just by spamming 1. The only exception is the worm. You need specific role etc. and it doesn´t work with just spamming 1. This is content we need.
Sorry for my bad english