The thing is, nano fully loads all syntaxes at startup (if the user has not edited /etc/nanorc to pick only those syntaxes that he/she needs).  With every syntax I add, the load time increases.  This is not a good idea for a small editor like nano.  We will first have to devise a system so that nano only loads the syntax that it needs at that moment.  But even then, it will have to load upfront all the recognition regexes, so that it can know what syntax to load for which file.  These changes are not trivial.

So, although I would like to add as many syntaxes as possible that are somehow useful, currently I try to add only things that are useful to a good number of users.

Printer Description files are something I think very few users will want to edit or even look at, so I don't think it's very useful to include the syntax file into nano's tarball.  Thanks for sharing, though.