I thought locale is mostly controlled by the environment. So you can run your system and each program with it's own separate locale settings if you like.

I wish there was a single letter universal locale with sane values, maybe call it U or E, with:

ISO (or RFC....) date time, UTF-8 default (maybe also alternative with ISO8859-1) decimal point in numbers and _ for thousands, metric paper / A4, ..., unicode neutral collation

but keeps US-English language