If a wrestler is going to secure one take-down per round and have it win the fight, I'd rather watch a wrestling-based fight for 12.5 minutes instead of 15.
And Squirrelfighter, you don't understand when it comes to cardio. Anyone at the UFC level can fight for 25 minutes. But it's a very conservative, low-risk fight. Fighters are free to use their gas tank more explosively and aggressively in a shorter fight, that point is not debatable. You simply can't be in good enough shape to go aggressive 100% for 25 minutes, human bodies don't work like that. Jose Aldo is a GREAT example. He gives almost the same amount of aggressiveness in his title fights as he did in the 15 minute fights, and he's always gassed and disengaged by round five.
sig credit to Limba