Being able to create microtonal scales is the attraction here for me, most synths whether they're digital or analog lock you into standard western scale tuning.
Some dubstep I've heard actually has quarter tones in it. If you find that everything you come up with on an equal temperament scale is boring and familiar, using different tunings and scales might be a useful next step to unlock creativity.
Something I still wonder though is how serious this microtonality thing is. Is it more of a gimmick or it there a serious demand for it?