Not to be an EA apologist or anything, but the NFL is the one that decided they wanted to only work with one game company. It wasn't the evil EA monopoly trying to push everybody out of the market. I'm sure EA had to pay through the nose for the license, probably much more than before it became exclusive.
The NFL and NFLPA didn't want to have to work with multiple companies. By going to one developer, they could handle all the data flow, face caps, etc. all at one time.