Vanilla WoW had a terrible endgame. It did great because even though it sucked it was still much better when compared to what existed at the time - EverQuest and Final Fantasy XI.
As for what makes it better, well, it's really the same. Get to the level cap, grind reputation for gear, run dungeons for better gear, run raids for the best gear. The difference is in the execution. Every time an expansion comes out end game is "reset" and everyone is starting over from scratch. When they release a new tier, you don't have to grind your way up the ladder to get to that tier.
Also if you don't care about running dungeons and raids, they have more stuff to do beyond that, along with a ton of battlegrounds and arena matches.
The big issue with Tera is two fold: Your options are limited (two dungeons, one quasi-raid, one battleground) and even if you successfully complete a dungeon there's no guarantee you'll get anything out of it.