> I don't see a good reason for  requiring all >127 actives.

For French. For English you could use 7bit TeX2, but in general to
support multiple input encodings that are different to the font encodings
you need them active. Changing catcodes anywhere causes multiple
problems (It's not at all clear that the slight convenience feature of
the \verb command was worth all the user errors and confusion it causes
with \verb being used in arguments). So if you can't change catcodes
and some encodings need the characters active, the only solution
appeared to be (back then) that all characters above 127 should be