SWTOR failed for one simple reason. they easy-moded -everything- and had no world. Even a casual could end up with amazing epic gear, and there wasn't anything overly special about the end-game instances that made them worth doing. PVP was really screwed up and a waste of time as well (although instanced pvp was fun).

The game was great.
The lack of "incentives" and the "easy mode" was not.

A good game catches your attention with the grind to max level. It's supposed to be a journey, and not a repetitive grind. SW TOR was more like a single player game made up of instances as opposed to an immersive game with a world.

An MMO needs 3 things for success
1. An immersive world
2. It has to feel like a journey
3. It has to have long-term goals with progression. Not random chances.

At the moment FFXIV's world is lacking in the immersiveness. FFXI pulled it off perfectly however. New zones should have no instant teleports (or only a few), and getting places should require avoiding aggro mobs. There should be "cool" things hidden all over the place, lots of alternative places to gather or fish, and a variety of different places to exp. Also exp spots should change every 3-6 levels.

FFXIV is too disorganized to feel like a journey. However I have a feeling they will fix this with 2.0.

FFXIV has progression for some things like luminary stuff, but has too much reliance on random stuff for equipment drops. FFXI's "once a week" thing worked really well as it forced linkshells to set a fixed time where they can bring all members along. This beats out the current system of lots of pick up parties or having to sit people out due to 8 ppl limits.