For years (ignoring how sensors have improved) the units limit the pool length to 15yards or 14 meters. Of course, these sizes aren't even accurate (after saving a length, say 15 yrds, it come is changed when viewing it in connect to 15.3 (14m). Except two of the most common lengths of home pools are 36ft (12yrds) and 40ft (13.3yards). Yes, these are not very big, but very common. Not all of use have Olympic sized pools to swim in. While I can understand not covering a 15' round pool, the common sizes should be supported (there is also a 32ft which is common)
For reference the common home rectangular pools are 10'x20', 16'x32', 18'x36', & 20'x40'. 20'x40' is actually considered extremely large for a home pool, with most people having a smaller pool especially if it is round or kidney shaped. So while yes 40' is not as ideal for training laps as a 25m or 50m they are what a lot of people have access to.
While it is nice that I can go back and edit the swim afterwards, it is annoying that I have to (especially deleting the numerous decimal places after choosing 15 yards, but really getting 14 meters). Also not sure why feet are not an option in the USA, given most home pools are measured in feet not yards or meters.