Midi is getting pretty popular with digital guitar pedals these days (see midi support on all Strymon, Chase Bliss, Meris, and Empress pedals). Midi is primarily used to change settings on the effects in bulk. Imagine a live setting where you have a pedal board with 10 fx and you need to switch settings on all those pedals to get the sound dialed in for the next song. You could do that with 1 button press on a midi enabled pedal board instead of manually changing the dials on all 10 pedals. Midi circuits and the protocol is pretty simple to implement, wouldn't be hard to add to something similar to the terrarium.