bigpaws: yes, but it you just include a tarball on its own with the original sources, that is still pretty useless because nobody knows how the package for that particular piece of software was built. Take Slackware an an example: why would Patrick Volkerding bother adding the the SlackBuilds?...because if he doesn't, then you can't make an exact copy of the package when building from source!
I can't remember where I saw an article abut this kind of thing, but Mepis is getting slammed for this very reason, and they are probably even more undermanned than we are...but what choice do they have but to comply!
metvas: yes, indeed, providing the source code is not as quick as just the binary packages, but its really not that much more work if scripts are used and if the packages are built with this objective in mind, ie: prepare a source directory, write a description, use a template build script if you want to speed things up, and run it. Sometimes things need tweaking, but thats nothing extraordinary.
Take exeterdad's Firefox language pack builder as an example:
http://vectorlinux.osuosl.org/veclinux-5.8/source/testing/net/firefox-lang/That script generates...a ton of packages which would have been a lot harder to do by hand, especially if things need to be changed in those packages at a later stage.
Well, I've made my point many times over so I'm gonna shut up now.