I think bug fixes is something you'd want. API changes less so.
My point was that there are frequently bug fixes and API changes since whatever version of gnulib is packaged in Debian.
Also note that gnulib is a piece that regularly faces portability issues
(as it tries to provide portability). As such, it is particularly
annoying for porters to not only have to fix gnulib, but then also have
to get it updated in tons of downstreams.
How is this a problem for Debian packagers? Once software is packaged for Debian, it's already known to build and run.
I stopped counting the number
of bug reports "... ships a broken, outdated, embedded copy of gnulib"
that I've sent. As a porter, I very much wish people wouldn't embed
gnulib.
I agree, gnulib as a whole shouldn't be embedded. I also agree that software that uses gnulib, even small parts of it (like libpaper) will have to update from time to time to fix bugs and portability problems.