Maybe its a matter of function......maybe.

Perhaps the MMA style knee strike--as described above-is more in the manner of "softening up" the guy. Most of the MMA/MT are in seriously hard condition and single knee is unlikely to work. But hit them with it a lot and the effects are compounded.

Maybe its a target of opportunity--you hit what's available?

Maybe its a question of timing? I've seen guys run right into a jab and cause themselves more damage than the jab alone.

Good question!

Sorry I don't have better thoughts right now. Still pretty early here. smile
I did battle with ignorance today.......and ignorance won. Huey.