I just commented the same thing. I can't imagine most applications would want to leak time information in their identifiers but these undoubtedly will be used most placed out of convenience. In a year or so we'll read about an attack and everyone will migrate back to v4 or have to maintain a cryptographic identifier in addition to their temporal identifier.
Most application may not want it, but will it hurt them?
I mean this is a similar concern to sequential IDs: many apps do not want to leak them, and in some cases it might cause issues, but in general it doesn't matter.
