This would kind of leave out every class/job that isn't MRD, GLA, or LNC. MNK skills are kind of combo-esque, but you don't use the same three in a row every time. AFAIK, none of the other classes really get anything like combos that could work with this. Some skills proc bonus effects, but you don't base their use entirely on those procs (e.g., BRD sometimes needs to use Straight Shot without a Heavier Shot proc).

While some classes just use more buttons than others, it seems kind of lopsided to give combo classes such a convenient, button-condensing feature while all the rest are stuck without it.