ToR failed where only WoW succeeded: graphics.
In WoW everything just visually fits. You notice exactly when you crit and how much damage each hit does; you know exactly which enemy of the 12 hitting you is bringimg your health down so quickly; you know exactly when your char performed an attack you told him to execute; et cetera.
This is something every single MMORPG except for WoW has failed to do.
Also in ToR's case there are too many ranged enemies due to lore, making it tedious to be a melee tank or dps and too easy and unengaging for a ranged player.
Last but not least, if Bioware spent less money giving every single quest character voice-over and more money making the main quests (planets + character) more engaging.. in other words if they made side-questing more like WoW and the main quests more like, say, Mass Effect / KoToR... this already would've been so so so much better.
But the graphics, that was a mistake since production day #1.