http://www.youhaventlived.com/qblog/...og190810A.html
One of the main problems is that it's very unrealistic. Yes, I know these are fantasy games but even in fantasy worlds most combatants would be intelligent enough to ignore the tank and go after the soft targets who are actually doing the damage, or keeping everyone alive.
Throwing out the traditional model of aggro, then creating a more realistic (or at least different) aggro model is a great way to get rid of the trinity and create a new fresh experience in mmos. And that doesn't mean kiting either. There are numerous ways to change things. Personally, I would look at how actual battles work and try to emulate that (using limited collision detection, etc). But there are other options.
Part of the problem with modern mmos is they are all based on the same basic building blocks that EQ copied from dikumuds. So of course the experience never really changes and we all get bored so quickly. Almost every mmo is just a copy of each other with a different artistic skin and some minor peripheral tweaks.
Blow up the basic rules that have been copied for way to long and come up with something new, that is the best chance at creating an experience that will be truly memorable and different from what we have now. If devs continue to copy the trinity then they are committing themselves to being a clone. You can still make money doing that but that path is very worn out, old and tired.