I for one am VERY happy with Nautilus and Ximian software. It's all free, so I can choose what I want to. And I didn't even paid Ximian anything yet. But I will do, as soon as possible. They deserve it.
Every distribution is free to package balsa.
Every distribution is free to NOT package it if they think, it's not needed anymore. Or whatever else. There are deb and rpm's of balsa, just not on the Ximian server. They didn't even include Netscape4, because they have Mozilla now. Why should they include every damn email client.