The key here is "reasonably priced". My first experience of Y+ was on BR over 10 years ago, and it was simply an economy seat with ~30% more space (seat footprint) that cost ~30% more. Nowadays the seat footprint is still the same, but it is priced much more than 30% more. And the seats don't actually feel much bigger than economy because of the in-arm equipment (at least on BA).

I don't mind paying a little more than 30% for 30% more space and an economy level service if the cabin is quieter. But I wouldn't pay double for 30% more seat space even if there is better food, service and bigger IFE screens etc.