Whats the damn story with this tiny problematic RootFS!?!?

My phone has hardly been used and the rootfs has 4mb of so left.
I uninstalled just about everything and tried apt-get clean and in the end I had 10.8mb left..

Why is it so small? Can it be enlarged and why would Nokia use such a small rootfs? There is PLENTY of space on the N900..

Please help, I'm new to linux and I don't understand how this can cause my phone to not even work when it fills up.

It became full once before for no reason so I decided to format the emmc and reflash.. I do not want to do it again.. Seems like a REALLY terrible design.

Why do programs install to rootfs?
I have been reading about installing .deb packages on here and they can fill the rootfs very fast... I don't understand this part of linux.. Sorry.

Also, I'm sure after I had uninstalled everything, the only extras-devel I have installed are: Power Kernel and Maemo Python (which I think I uninstalled, too).