Have you played any competitive Meltdown matches? Not just Pub-Stomping? Metldown has the highest room for making playsand changing the entire match. It is exciting to watch from an audience view. Incursion is not exciting to watch. Why? Because of how easy it is to play defensively.
No, Map control is absolutely everything in ANY competitive game whether it be a FPS, MOBA, RTS. TTK has no difference in it at all. Map control gives more options. It should ALWAYS be the goal to have map control. Incursion does not promote that. Why? Because the things people obtain in the middle of the map are not important enough to have a great affect of whether or not there will be a winner.
Instead of Mid thralls, have a mob there that when killed gives the teams minions an overshield and damge buff to Sentry. Now Middle control is important to contest over.