In about 4 months the UK is scheduled to leave the EU.
Probably some portion hope to revert completely when they do.
Probably some portion hope that they rejoin the EU with another vote; and in the process get dragged the rest of the way to the engineering age measurements in the process.
Well, for rooms with actual tatami mats, you are not really interested in the area, but rather how many mats will fit.
Thus, a 24m^2 (12 mat) room with the wrong aspect ratio will not fit 12 mats. (I'm using the 1 mat = 2m^2 conversion for convenience and I actually use 2m^2 mats in my tatami room.)
Practically, mat sizes can vary a bit and can be custom sized. [1]
Even though today only a minority of apartment rooms are actually used with tatami it is still customary to give all rooms in mat units and usually in m^2 too.
BTW that's similar to how non SI units are still used in other countries nowadays, e.g. (metric) pounds and half-pounds are still used in context of groceries in colloquial German.
The UK left the EU at the end of January 2020. The EU is currently treating us as having various member agreements in place until the end of December 2020 but we have already left at this point.
Probably some portion hope to revert completely when they do.
Probably some portion hope that they rejoin the EU with another vote; and in the process get dragged the rest of the way to the engineering age measurements in the process.