Niche in the sense that there are relatively few beekeepers in the UK who use one size box. I'm not suggesting it is either a good idea or not a good idea ... but ... the Rose method has been around for quite a long time ... and Warre - which is also a one box system, even longer ... but neither are mainstream in the UK - hence my comments about how long things to catch on or, indeed, if they ever will.
There is little logic in relation to what bees require about most of the beehive box sizes we have available either here in the UK or internationally for that matter. Abbe Warre used champagne crates which were readily available as his basis for his boxes. British nationals came about as a result of the size of timber economically available at a time when timber was a precious resource ...
What the bees wanted does not seem to have come into most considerations ... if they did - what do you think they would ask for ... and then .. how would it be used by beekeepers to econmomically and effectively keep them ?
Eloquent and succinct.
I think bees might ask for deeper frames.