Poor sales is the obvious answer to me. Think about it, out of all the music acts you see working, how many use an arranger. Its either a live band, sing to MP3's with a computer, or, God Forbid, a Kareoke DJ !!!!
And for the home hobbiest it would be the price. The BK5 is more than enough for most home players. If they're more serious into home recording a workstation and computer would be a better fit.
Just my $.02
Bill all valid points....but, why is it that Yamaha, Korg, etc, are doing a thriving Arranger KB business worldwide...unless Roland's other musical divisions can carry them along without offering any TOTL arrangers KB's anymore, Sales have to be a factor,......I see more Fanthom Kbs in many stage acts vs any arrangers at all for bands......