COIN (or 'asymmetrical warfare' as it is also known) does indeed require additional skill sets. There will always be the need to fight and win kinetic engagements.

Further, our military, after a learning curve, now has the skills to win in asymmetrical environments. Its still a shame that we deploy them, only to not let them win.

The common factor in US failures in modern asymmetrical conflict is the lack of political will to let our best men and women do what they are trained to do. Once the decision is made to send them, don't tie their hands because your poll numbers might take a hit. Because more than anything else, America loves a winner. A fine example was the engagement at Tora Bora. We had, supposedly, OBL surrounded. But our politicians (in this case, the hated GWB) wanted to look like a 'team' player and wait for (unreliable at best) Afghan forces to get to the battlefield. In battle, when you have the enemy on the ropes, you stomp on him.