Conor McGregor views himself on the same level as the UFC, and as a partner, not subordinate, due to the amount of business he brings them. Their recent success is largely tied to him, with him being responsible for a large share of the revenue.
The UFC has all of its fighters go through a string of media obligations. TV talk shows, Radio shows, press conferences.
Conor feels that he isn't just some regular employee, and thus he doesn't want to do the regular media run. He wants to decide what he media he wants to do. He feels a lot of the media is in poor taste and/or pointless, for example that shitshow on Good Morning America this morning. He's particularly dissatisfied with these media obligations for 3 further reasons:
First is that he's had to do more media than any other fighter, so he's naturally more burnt out than others. Second is that he delivers original content in media appearances, whereas other fighters give stock answers, so he has to work more in his obligations. Third is that he has stepped up in times where other fighters haven't in accepting short notice replacements, so he feels he deserves leeway for that reason.
All of this is exacerbated by the fact that he's just suffered his first UFC loss. Conor is a fighter fueled by his own extreme self belief, so it's especially important for him to focus on correcting the holes that were exposed in his game in the Diaz fight.
The UFC doesn't view Conor as an equal. He's just another employee (technically he's an independent contractor), albeit one who produces a huge amount of revenue for them. They want to keep him in line with the other fighters, so don't want to make too many exceptions for him. In some ways, I'm sure they've made some exceptions already. But they weren't happy with his requests this time around, so they pulled him from the card. The UFC has chosen to take a big short term financial hit, in order to avoid setting a bad precedent.
On the surface, this is a negotiation about media obligations. Behind that, it's a power play between promoter and fighter.