I have stated too strong an opinion. It probably should have read
``there are languages for which global defaults don't seem to be such
a good idea''. So now I propose the following scheme:
Document preamble can contain commands of the following kind (a better
command name is needed):
That means that every fragment of the document marked as written in
french is to be treated as latin1 and typeset with T1 fonts.
Accordingly for fragments marked as polish text.
Obviously it should be possible to override these settings with usual
encoding selection commands inside apropriate text fragments.
\DeclareLanguageEncodings could also be put directly in the language
definition files thus serving as global per language default.
(I haven't seen babel 3.7, so I don't know how does this fit with the