A good jab could be used but only against certain styles. Against a takedown artist it is going to be more of a liability. That being said I don't know why grapplers don't attempt to work takedowns off of a good double jab. I'm barely a novice as far as my mma fighting experience but I've often had good luck with pumping a strong jab then shooting for a single leg take down. To me a really good snapping leg kick is to mma what a dominating jab is to boxing. A fighter that can land hard leg kicks and work combos off them can be very effective. You rarely see this employed. I'll take my hat off to Cung Lee this is a tactic he is very good at. Of course there is a risk/reward concerning the possibility of a takedown but I think it is the future of top standup fighters. MMA offers such a small margin of error. As fighters become more and more proficient strikers this margin will decline even more. Quite often now when I watch two really talented fighters it seems they are just waiting to see who will over extend themselves or make a mistake first.