I've said it before too
And I'll say it again, it's a matter of convenience and one of safety, not necessarily determined by the size of a property.
If cylinders/canisters are designed fit for purpose to be supposedly better at cleaning than uprights with short hoses, and less likely hood to cause injury since canisters rarely fall back, then it makes sense to EITHER offer a longer hose or longer cord. It makes sense, particularly for cleaning awkward and difficult to clean areas that you'd never dream of taking an upright vacuum cleaner to do.
Case in point - my loft was recently re-insulated a day ago There are no power points up there since I live in a low roof property. The mess left afterwards though meant that a vacuum cleaner had to be used to suck up the left over fragments of fibreglass. In this respect the Sebo D2 was carried upstairs to the loft and it performed well - the longer 12 metre power cord stretched up from the hall way, up the ladder and literally the men could pull the machine all around the shape of the loft floor to get up the last of the excess mess. If I had given them my Miele canister, it would have had to sit precariously at the entrance of the lift against the ladder in the hope that it wouldn't fall over and it wouldn't be able to travel as much around the loft.
I could use an extension cord on any of my vacuums with short cords - but I really don't see the point - a long cord is a good benefit to minimise tripping over extension cords as well as spending the time wrapping them up (surely to god if someone is out there reading this who is an inventor, it would make sense to offer an auto cord rewind extension cord?!) after use. Maybe the U.S have them - but the UK don't generally have long power cord reels with an auto cord rewind function.