I think you cannot make each software package maintainer to use your
new tool. And, anyway, most people are fine with man pages. If there
is one...
But it is indeed possible to use modern tools to create textual
documentation. With xmlto you can create man pages (and other formats)
from the same docbook source. Yesterday I started using it and having
found a basic docbook xml source I was able to write a small man page
in two hours.
Now the documentation project is in favor of the Publican system,
which is yet unable to create man pages.
- Gergely