iTunes is to playing music, what maven is to building software; a ponderous self-regarding busy-body more concerned with its own housekeeping than serving users.
iTunes: You'd like to play some music? I'll be with you in a few moments. Please wait while I download and update myself, quicktime and safari.
Maven: You'd like to build your Java source tree? I'll be with you in a few moments. Please wait while I download a couple of hundred plugins and dependencies from the repositories.