why not ?
Eried has done a great job for windows,
I'm certain that the clever people here can make installers for other systems just as easily.
For for many of the other more modern operating systems it isn't necessary
as there is no need to have to do crazy stuff inside the application for installs & updates
like you have to do in legacy operating systems like Windows.
This is because the operating systems have a built in packaging system that handles
installs and updates for all the applications in common and consistent way that
does not require the actual application to be involved with the process.
So I think this is mostly an issue for Windows applications.
And even that problem might finally start to go away if there is a way to use the Microsoft
Widows 8 app store for "free" apps like the "Arduino" s/w.
why not have separate people responsible for each installer ?
see what open source can do.
Open source has already solved this problem.
On the "nix" based systems, which is just about all the other OSs out there
including OSX, a common installer is already provided by the OS
and already exists and works pretty well.
On debian based systems,
you can simply go to the package/software manager and install the "Arduino" package.
In the future, the update manager can notify you of an available update.
There is no work that needs to be done.
What might be useful is to have someone work closer with the repository maintainers
to get them updated with new Arduino releases sooner if there is a desire to push
out the newer Arduino releases sooner.
My view is that an Arduino library installer inside the IDE would be a much more useful
tool. Some kind of interface that would allow users to point at a library and then have the IDE
install the library in the proper location.
This is something that would be useful for all the OS's.