I kept wondering why my motd file (/etc/motd) kept reverting on reboot… so I took a little looksy and noticed it symlinks to /var/run/motd, which is in turn populated by some lines in /etc/init.d/bootmisc.sh.
All you have to do to prevent that is to remove the symlink e.g rm -f /etc/motd and then create a ‘regular’ file with whatever fancy content you want 
Personally im a fan of Network Science Ascii Generator for generating some pretty ascii text…