Yes, the whole world has to use ASCII for their WPA-/WPA2-PSK passphrases.
This may not be a big a burden as you may think, as ASCII has been so pervasive in computing since it was first invented, that the computer-using populace worldwide is well versed in using ASCII. For example, hostnames and domain names were ASCII-only for quite a long time (have internationalized (Unicode-based) domain names even caught on anywhere yet?). Most programming languages are still ASCII-only, or "Unicode-unfriendly" at best. Command-line environments tend to also be ASCII-only or Unicode-unfriendly, etc.
Because of this legacy, understanding how to deal with ASCII is, sadly, just a part of becoming "computer literate" in any culture.