After rewatching Jon Jones vs Ryan Bader the other night, I began to wonder about headbutts to the body. 

In the first round, Jones is seen throwing what I would call "chin thrusts" to Bader's body from north/south position. Those weren't exactly headbutts, but I suppose they were looked at as such, and warranted a warning from the ref. They seemed relatively harmless though, the type of strike more likely to annoy an opponent than to cause anything near actual fight ending damage. I suppose in that respect, they could be likened to foot stomps.

It got me thinking.  Why are headbutts to the body illegal?

I can understand why to the head they're illegal, but when thrown to the body, it seems to be a perfectly fine way to keep busy on the ground. One more way to strike. One more thing to look out for.

They just don't seem to fit the criteria the same as other illegal strikes.

So have I overlooked something?  Do you guys agree that they might as well be legal?