As great as the Kirby vacuums truly are, I see mainly two problems with them.
1) unfortunate high pressure and sometimes shady sales practices of distributors, especially targeting the elderly (this has often gotten them negative media attention).
2) the machines, although certainly versatile and different than anything else on the market, I think are just too fussy and complex for the average user. Having to take the head off to put the hose on for the normal person that just wants to do a quick vacuum is very inconvenient. Also all of the accessories, while novel, just never get used, and sometimes lost.
How many times do we see Kirby vacuums for sale or at the thrift stores, and the attachments and accessories are all just in a jumble and clearly never used? Or the seller has no idea what any of it does, nor do they care. The owner likely never bothered to figure out what is what or how to use any of it.
I just think Kirby really doesn't fit in today's market. The older generation saw the beauty in, and cherished things like Sunbeam Mixmasters and all that they could do.
Today's generation is too busy with electronics, work, and other sort of things to have any interest in all that the Kirby can do.
The older generation has largely passed away. Tools on board uprights, and bagless vacs have been on the market for nearly 30 years now, and that's what people are used to. The market for Kirby vacuums is fading away and I don't see younger people as a whole being interested in them. The only ones I could see would be people like stay at home homesteading moms that have time to figure it out and lots of cleaning to do.
I'm not even sure the Kirby vacuums of the past were even bought because people actually WANTED them. I think it was high pressure sales tactics as well as claims of all that the vacuum could do, and maybe a person who just happened to be in need of a new vac when the salesman happened to knock on the door.
But quickly, the owner found out it was too heavy and too confusing for what they wanted, so the vacuum never got used, or if so only in floor mode.