MIDI is pretty awesome. It allows you to have a ton of control over your effects. One of the main things pedals use MIDI for is to sync to the beat. Imagine tremolo or delay always being right on the beat, or syncing to exactly a triplet of the beat.
However, putting MIDI jacks on your pedals kinda sucks. Most musicians don't use MIDI, so adding the MIDI connectors is both cost and space prohibitive. With the Empress Midibox, you can sidestep these issues. You can have one jack on your pedal available for both MIDI input and expression pedal input.
Email Steve at firstname.lastname@example.org if you're interested.