What I've gathered from the JP forums is that they have this ideal way to see the jobs.
Healers only job is to heal. No damage what so ever, only the bare minimum. (I kinda agree. But I feel like there is a need for healer rework... at least for sage. [It's failure of a DPS healer])
Tanks need selfsustain more than anything. Actually there isn't enogh! (I know tanks need those skills but absolutely no nerfing of them of any kind?)
DPS is just DPS. All about damage.