You have to admit, the normal situation makes life easier in a way:
You end up with three kinds of people:
1) The people who have their own computer, with root access, and can install anything they like.
2) The people who's computer is managed by someone else, and they can install nothing.
3) A few people who can think well enough to install binary tarballs, or if the appropriate toolchain is installed on their computer, they can actually compile from source code.
It certainly simplifies things for the package maintainers - they don't have to bother looking to see if root is installing the package, and therefore everyone can use the program, or if a user is installing the package, in which case the files should be stored in *THEIR* home directory, and the program is not available to everyone else.
Of course, how many admins actually want to give their users access to something like a compiler! That's just asking for them to be able to use their computers in ways the admin doesn't want them to.