A stomp is a lot more than a forward thrust kick, particularly since a stomp is normally aimed at the head and a forward thrust kick isn't. It's the same as an elbow from the 12 to 6 position which is a lot more dangerous than an elbow thrown from the 3 to 9 position, regardless of what Joe Rogan says. Go watch some old Shogun and Wanderlei Silva fights from Pride and you'll see how much force you can put behind a stomp that isn't possible with a forward thrust kick.

I'm all for allowing kicks and knees to the head of a downed opponent.

What they really need to change is allowing up-kicks to the head of your opponent when you're on your back. It's ridiculous that that isn't allowed.