because is ugly 
well yeah, basically, not very user-friendly (example: my mom would not be able to install software with it), instead, we are using a different one which is much more friendly (my mom, would be able using this one), the only thing that we need to know is that it works correctly and without issues
BTW, since this one is a bit more huge in resources, the 32-bit version uses synaptic instead of that one
clean install, and don't believe in tools that claims that can convert your filesystems, its dangerous and you can lose your data
by other side i dont think is too important to switch from ext4 to reiserfs unless you feel the computer slow, but you may not notice really an improvement
