While I agree with most of your observations, I must also bring up that some of us are at least partly responsible for the fact that the stores don't carry much in the way of arrangers.
How many times have we sought out a dealer and demoed his merchandise, then went back home and bought one over the internet to save money?
It does take money to properly train and compensate a good salesman. It's my belief that in the not-too-distant future there will be only a single handful of music stores in the U.S. Almost all of the individually-owned stores will be forced out of business by the huge internet stores, much as Walmart has caused so many small businesses in small towns to close. The reason for this is that the huge stores can operate on a volume that allows them to make less profit on an individual sale, particulary when they don't have a huge staff of highly-trained sales people.
I have discussed this very situation with my local store. Their point of view is "Why should we invest thousands of dollars in these keyboards when we can use that same money to buy other items on which we can make a much higher profit?"
It takes longer to educate a customer and properly demo an arranger than it does a 7-foot grand piano. One grand piano sale can make the store more money than 25 arranger sales, particularly in the low-end price range of arrangers.
I am told that some of the manufacturers have taken steps to try to make the small stores more competitive in recent years, but it may be too little, too late.
Gary, I also spent some time at the store years ago, selling the early arrangers and organs. At that time you could price a Yamaha PSR 5700, or a PSR70 at a point where the store, the salesman and Yamaha could all make money. If you try to do that now, the customer is savvy enough to go to Sam's Club or Circuit City and buy a WK3200 for $299., or scour the internet for the best deal, with free delivery and no sales tax, AFTER you have spent a couple hours selling him. For sure Circuit City has no one that even knows how to turn the WK on, much less compare the features to something like a Tyros 2, but guess how will sell more keyboards?
This most certainly isn't the entire problem, but I feel it contributes greatly to it.
DonM