and other common shortcuts for that matter?
convenience. in a GUI world, switching from the mouse to the keyboard and back again sucks. as does making a user have to look up (via ant -projecthelp) the actual build instruction when there can be several depending on the size of the distribution.
So having a few .bat files for the most common tasks that a non-developer would have, like having a quick "installme" script that would do "./configure; make; make install" with most autoconf-driven packages, can make things easier for users who just need the stuff without needing to know why it works or how to make it work in detail. somedays i just want the .jar, and i don't really want to dig into the buildfile to figure out what to call to get it.