There's foot grunt AI that moves like normal infantry. They are there, like creeps, to give the sense that you are part of a larger battle. They are also relatively easy to kill from what has been revealed. Is that an appeal to casual players? Maybe.
There are certain things inherent to lower player count games that just don't go away with the inclusion of AI grunts. People have played the small playercount stuff before on console. As a PC player, I was hoping for more. Way more. Even if that meant making Titans more rare or whatever it takes.