I thought about making the first one selected be marked in some special way (currently its possible moves are the larger circle), but unfortunately it's something I thought of after submissions closed. Had I had time to work on the game Sunday, it would definitely have made it in.
I'm hesitant on allowing single piece movement, partly becuase of the Jam theme, but also because I like the "united we stand, divided we fall" thing, which is one of the possible victory conditions. Like I mentioned in another comment, I have multiple ideas brewing (including playing against the computer)