I'm just waking up to the news about the grunts.
If you are questioning and still don't understand the point of grunts of TF1 even just for the sake of the point system (and not even that they were always tactically placed to aid in the flow of the match, fill the larger maps), then there's really no point in explaining it for TF2. Over 23+ days worth of game time for TF1 here.
If there is only one mode with grunts and they left this game to die a boring death by just leaving pilots and titans, this game is a no buy for me.