Cillian,
  I think I missed a bunch.  :)

Only so many hours in the day. 
You're right, I didn't talk about firefox, perl, python, ... having their own way of installing stuff.  I rambled enough as it is, I'd hate to imagine how much more I would have had I brought those up.  yaourt (pacman alternative for arch linux)  has that ability and ebuild also can do that with perl.  It'd be really cool if that was a more standard thing.  Thanks for listening and the comment!

Kyashii,
   There's nothing fashionable about it from my perspective.  I've heard almost noone complain of package system proliferation, in any of the forums, chatrooms,  mailing lists or news aggretators that I visit regularly.  In fact, I hear exactly the opposite on a fairly regular basis.  Someone excited about their project,  a new package manager that either fixes a certain problem in another one or a fun project they have been  'kicking around and have been working on for the last 6 months'  Possibly we hang out in different areas though.

   I don't see packaging as similar to the 'everyone runs GNOME, KDE, ....  argument.  Those are about choice. Please refer to my comments about 'things able to run on the same system'

  I don't believe the file system heirarchy or dynamic vs static libs or system init scripts as unscalable walls.  Are there differences to be figured out? Of course,  but a file that lies on libcups.so.1.2 or libcups.a relies on that library regardless of where it lives.  (use /etc/ld.so.conf)  THings like how the daemon gets started, obviously depends on the particular system, but to say that things like this make it impossible to have one packaging system but still allow multiple distros is something that I don't believe.    Thanks for listening and commenting.