I'd love the option to allow more enemies to a street battle if I want to so that rather than two at a time, I could let up to a full group of four enemies into the battle. This would help to speed up the game in some defeat and collect and farming situations.
This idea has been floating around in my head too. I think there should be a restriction on it however, such as meeting a certain level requirement before allowing more than 2 enemies into a solo street fight.