From the entertainer's viewpiont:
Organs are big, very expensive and as a rule can't be updated. They can't be easily moved.
I was never so happy as the day I graduated from organs to arrangers, even though at that time arrangers were primitive and I needed outboard gear also. I used an external drum machine, DX7 for lead sounds and piano module for piano.
Still, no organ, leslie, dolly, bench, pedalboard, etc. to lug around.
I recently heard a guy played the latest and greatest Lowrey organ. I believe he said it cost around $20,000. It weighed a ton and it sounded like a skating rink. I'm sure he wasn't getting the most out of it, BUT, who cares--it was too big, too costly and too restrictive.
DonM