I beg your pardon (ha, ha) I was into and purchased many Organs when I was 20's - 40's. They were terrific! Many of the Organ players in Japan are young as well.
I think you are correct...the target for arrangers is folks that had Organs a while ago. Probably older folks now as Organs went away in the US in the 90's. Also, Pro's gigging out and a few young people too(wish there were more)....I used to have Wurlitzer, Thomas and lastly Yamaha. They were all great...but my favorite was the Thomas for style etc(had a real Leslie inside) and Yamaha for the sounds. Today you can get a Yamaha Organ in Japan (about $8,500 +...maybe some other places) but not here. It's a pretty cool instrument.
It IMHO is really an arranger with lower manual, and pedals. Of course you can do that setup nicely with and arranger too. Most folks are content to just skip the pedals, and use split for the 2 manuals instead.

I still like the lower manual, lots of room for chords AND use it also to play RH stuff on the lower (and can do bridging) pedals would also be nice, but not required as we have great bass in the styles already that we used to have to play with pedals.

To me it's still ONE MAN BAND...if you are a PRO and good singer...a stage piano, and or audio backing tracks works well (I see a lot of that here in my 55+ community, 10,000 people here and 25 miles from the Villages with 140,000)

I do wander what will become of arrangers when most of us old geezers go to a better place??