Note that the question is not "Shall we support Unicode?". Clearly we should.
The question is rather whether it would have been better to gradually improve support for it in a Python2-esque way, rather than creating a discontinuity and a raft of new problems, some of which linger to this day.
Also, for many purposes, there is wide agreement that ASCII is still the way to go. Even if Americans vanished tomorrow, the majority of remaining programmers in the world would prefer to look at source code in English, which they already know, rather than a host of other languages, most of which they don't.