You dont see it often compared to say boxing because 1) they're not boxers duh, but 2) and most importantly because of all the variery of strikes and threat of a takedown these guys have to be a lot farther than from each other in a striking battle.
You can see how good of a boxer Stipe is though for a MMA guy. Those body shots were fast and crisp and the way he set them up were beautiful.
I love seeing body shot KO's because no matter how tough a dude is or how great their chin is. A perfectly placed body will always bring them to their knees.
For example Stephens against Aldo. Stephens is one of the toughest dudes in the UFC and the way he was wincing in pain and crumbled to the ground is so shocking lol.