Data drawn from Sierra and wikipedia, it shows that the 140 grain creedmoor has a much better ballistic coefficient than the 150 grain .308, and it only sacrifices 100 fps or so in velocity; I didn't go through the ballistics charts, but I am presuming that the creedmoor will give usefully flatter trajectories and greater remaining energy out past 200, and I personally believe that with good, controlled expansion bullets it would work just as well, or maybe even better, than a .308 in bigger game. It's fully capable of blow through on big animals with that high sd.
Just for the purposes of discussion, it's really obvious that the CM is a great cartridge, and that it can serve quite well as a large game long range round, lower recoil, short action, flat, fast, capable of excellent accuracy.
For practical purposes, though, the entire question is answered with a big "so what? The others do just as well for me". Most of those rifles loaded for the creedmoor, I truly believe, gain very little, or no advantage, because there is no benefit to be gained at the ranges where the 6.5 actually shows an edge. I've never hunted anywhere that really provided shots beyond 300. My preferred game rifle is a .243, if I ever hunted beyond 200 or so, I'd carry my 30-06, If I ever had the opportunity to hunt longer range, I'd have to get a newer, more accurate rifle, better optics, and since the option would be available, i would definitely consider buying a 6.5 creedmoor.