Don't laugh but my vision for SAM is kinda almost support.
What made me love SAM was the SAM in xi, and I know it was a dps but in some ways it could be considered partly support. You had to remember all the combinations of weapon skills you could do between the SAM and the other members of your party and what skill chains you could produce from them. Remembering that doing X w/skill so your drg/thf whatever could follow it up with w/skill Y to get extra dmg from skillchain Z was great fun. You had to remember the weaponskills of all the different classes and coordinate with the other people in your party to maximise damage. SAM was king of skill chaining.
Obvs we can't have that in ARR but we could have a dps that uses skills to weaken a mob to a particular attack. Imagine SAM uses skill A which weakens the mob for a few seconds to damage type B allowing your drg or to get extra dmg from his skill or your BLM to do more dmg or even to extend DoT times.