UFC 200 is an event that Dana White and the rest of the UFC wanted to make extremely enticing for fans. UFC 100 was the most watched Pay-Per-View in the history of the sport, so, obviously, they want to try and go even bigger at 200.
A rematch between Conor McGregor and Nate Diaz had been rumored for a little while to be the headline event, and it was confirmed earlier this week. After it was announced, many people questioned why. Finally, we have our answer: White said McGregor begged for the fight.
White said he tried to convince McGregor to go down to 145 pounds and defend his featherweight title next, but McGregor was having none of it and only wanted to fight Diaz next. There have also been questions about having the rematch at 170 pounds again, which is where the first fight took place, but McGregor insisted on that too.
Diaz and McGregor fought at 170 pounds at UFC 196 because Diaz had been fighting at welterweight and only had less than two week's notice for the fight and didn't have time to drop the weight. White and McGregor's coach suggested the rematch be done at 155 pounds, which is Diaz's natural fighting weight and closer to McGregor's natural fighting weight, but, again, McGregor refused.
Before losing to Diaz in the beginning of March, McGregor had won his last 15 fights. The fact that he got used to winning every one of his fights probably plays a part in him wanting a rematch at the exact same weight. The Notorious is out to prove that that loss was a fluke and he will now have a full allotment of preparation time to do so.
The first McGregor vs. Diaz fight drew a ton of attention and headlined the most successful Pay-Per-View in UFC history, so the fact that the promotion opted for a rematch isn't a surprise. Having said that though, there are plenty of people who would have preferred McGregor drop back down to 145 pounds to defend his title. The good news for those people is that Frankie Edgar will take on Jose Aldo at UFC 200 for the interim title, and White guaranteed that McGregor will face the winner next "win, lose or draw."