I've been wondering the reasons:
Too bulky for most folk?
Insipid suction power (based on the EU maximum motor wattage)?
Too expensive?
Or maybe they were just plain unusable?
I remember reading customer reviews last year, which said the floor head on the cylinders stuck fast to the carpets, balled and rolled up pet hair - but didn't actually suck it up!
Perhaps it was an exercise by Dyson to deliberately make the machines unusable, so that nobody would buy them, and thus they could discontinue them. It wouldn't surprise me in the least.
The Dyson uprights are proving to be awkward for some customers too: tools very awkward to use, cleaner head sticks fast to the carpet despite the slide control, handle-lock non-existent, plastic components breaking, noise levels, blockages, poor instructions, and a mains flex which is too rigid. The complaints are from folk who owned previous Dyson machines.