Maybe it's a kind of chain reaction. Roland didn't have any arranger of that price range for several years. Now it's difficult to get back into business in that segment, as most dealers probably don't even have any BK-9s on display to try it in the store. Typical self-enhancing process where cause and effect blurr: Dealers don't order a display unit as they anticipate lacking demand, so no customer can test it, and nobody buys it. Etc.
Additionally, marketing was bad in the beginning, and many buyers are too much focused on visual aspects, if they see a big touchscreen they think the sounds are better, and those two small displays put them off.
AND it's Roland's own fault as they didn't deliver the tone expansions they announced.