Comment by jeroenhd
The invariant locale can't parse the numbers I enter (my locale uses comma as a decimal separator). More than a few applications will reject perfectly valid numbers. Intel's driver control panel was even so fucked up that I needed to change my locale to make it parse its own UI layout files.
Defaulting to ROOT makes a lot of sense for internal constants, like in the example in this article, but defaulting to ROOT for everything just exposes the problems that caused Sun to use the user locale by default in the first place.
Agreed, there are cases where user locale is needed. So many so that I expect that to be devs’ default if required to specify, and that they won’t use ROOT where they should.