I'll be partly reiterating myself too:
* Following Debian testing is a lot of work and Trisquel does not have the
adequate work force. Same observation for biannual releases.
* Most of the technical work achieved in the Trisquel project is writing
package helpers (not theming). Basing Trisquel on Debian (rather than
Ubuntu) would not ease the work because Ubuntu does not add freedom issues,
except for the kernel (but the deblobbing script already exists). Try to
list the package helpers in
https://devel.trisquel.info/trisquel/package-helpers/tree/flidas/helpers that
would become moot if the package was taken from Debian's repositories instead
of Ubuntu's.
* Defaults matter a lot. Look around you: many people keep Windows' default
wallpaper by fear of altering anything! In fact, the main reason why people
use Windows is because it comes by default on their computers. Defaults even
matter for highly technical users. For instance, one of the main critics to
OpenSSL library is its insecure default configuration: most of the
applications using it were keeping that insecure default configuration. I
guess most users of Trisquel keep its default desktop environment. It is
hard to prove that point though: the less skilled users (for example my
parents and my brother, who exclusively use Trisquel) do not actively
participate in the community. Many (most?) users cannot choose their
applications from a list, by lack of knowledge. They have no idea what
difference it makes to choose MATE or GNOME or KDE or Xfce or... if they even
know what a desktop environment is. And it is perfectly fine: users should
be able to easily free themselves, without having to know the names of the
different free software programs.
* The Trisquel project has never dealt with "excelling the free drivers",
"finding better substitutes for popular non-free apps", "polishing them",
"developing a knowlegde/solution base for utilising unfriendly hardware and
protocols", contrary to what you seem to believe. Almost no distribution
does. Because that work had better be achieved upstream. Not at the level
of the distribution. So that all distributions can profit from that work.
