I've seen the looping thing done by a few guitarists here. Is entertaining to watch them build the song but then repetive and boring. The fad seems to have faded.
As for new players using Arrangers ? I just think its a lack of exposure and not being able to shake the stigma of the toy like arranger keyboards of the past.
When I play no one knows what I'm doing to get all the music out nor do they care. Its the final product and it seems to work pretty well for me. I do enjoy working with my sax player as it adds a bit of realism to the sound as people can relate to a sax better than an Arranger.
Finally , you just never see Arrangers in stores much. Too expensive to stock them so again , limited exposure.