I think the term "arpeggio" has been badly twisted from it's original meaning when it comes to what things like the Motif does. It blurs the lines between styles and arps, but really it doesn't do styles as well as an arranger does. An arranger keyboard has dedicated patterns related to verses, choruses, intros and ending and fill-to's arranged in the stereotypical western pop music tradition. Arps can be anything at all and rarely fall into categories we would easily recognize as verses or choruses. Arpeggios on most keyboards are just rather simplistic note runs based on chords. In Motif-world "arpeggios" has looser meaning and seem to be based on individual instrument strums and licks way more than "combination" arpeggios that feature all of the instruments in the "band". True, there are some Motif arps with combination drums/bass/guitar riffs but those are the exception and not the rule. Mostly there are independent arps that you use as phrases for building song patterns. That's far more time-consuming than the styles of an arranger, where easily recognized and applicable phrases that always consist of "full band" instrument conbinations are instantly available at the press of a button.

It's the goal that is important: styles are far better for stage performance of popular music as well as for people who are not well-versed at composing that want quick results. Motifs and the like are totally build-your-song-from-the-ground-up instruments that give you some shortcuts (arps) to get you going.