Basically an inefficient method that has hung around since the first prototypes... Initially there were going to be relays, so it made more sense to have the 5V supply.
I can't remember but I probably just left the 78l05 off and jumpered the in and out and ran everything at 9 volts. The power supply on the daisy can handle 17 volts. (Edit: I looked at my modded Terrarium and that's exactly what I did).
