Er, well, the latter is much more potentially interesting?
Well, there's a concrete example here; CoX did perfectly well for many years with zero end-game grind other than occasional Hami raids, but with facilities for rampant altoholism.
On the face of it, it seems to me that if one must repeat the same content - and given that content can only be written so fast, one must if one is to stay with the game - repeating it with radically different powers is much more interesting than repeating it with the same powers for the chance of a purple drop. But, all the evidence says I'm the exception there. :-/
Except that incarnate trials were not a grind...
In other mmos you roll for the loot; in incarnate trials everyone gets something.
In other mmos loot drops and often times not the part you need; in incarnate trials you can convert pieces you dont need for what you actually do need.
In other mmos you need a gear score; in incarnate trials a fresh level 50 could participate due to the scaling difficulty of older to new trials.
In other mmos previous raid content becomes obsolite; In incarnate trials every trial could be run to make progress towards all incarnate powers and rewards.
In other mmos you need a tank and healers no exceptions; In incarnate trials, hell all of CoX this generally wasn't needed but it helped
In other mmos when you die you have to wait until everyone is out of combat and try again; In incarnate trials you hospital and wait on a very short timer or be revived. And with no harsh limits on reviving like other mmos have.
In other mmos you may never get your loot; In incarnate trials even if you only get threads you will eventually be able to put pieces together.
I'm sure If I stopped to think for awhile I could add more pros for cox form of endgame because it's simply not fair to compare it to the overused system other games have.
I know I'm biased because I love incarnate trials but honestly If we never got incarnate trials I probably wouldn't have played nearly as much as I had. I was at the point where the options on what to do were getting limited after countless alts. Same for my friends and like many of us had requested for years... "Give us more to do with our 50's" and we finally got it!