You're focusing way too much on this.
The point is to make an engaging video game which will grab consumers regardless of content. That Tiburon has the NFL brand automatically grabs an audience - those who like to play NFL football - but that doesn't mean that they can't expand the pool of potential customers to those who aren't a part of that audience. Part of the reason Ultimate Team exists - outside of being a micro transaction engine - is to add a collectible card game component into Madden, thus creating a game that is both a sports game and a resource-management game within a game, thus creating a total package which appeals to more people beyond only those who want to play NFL football.
Coming at it from another angle - why is Tiburon is spending so much time expanding the Madden Skills Trainer? I think it's rather obvious that these things exist it's to teach people who haven't played Madden or football before how to play the video game that is Madden NFL, so that the barrier of entry to sports games - which is very high to those not familiar with the sport for multiple reasons - may be lowered, thus more people may become interested in and buy the game.
Speaking more personally with respect to games with engaging mechanics - I don't particularly enjoy the sport of racing, yet I have a ton of fun with Forza Motorsport because it's a well-designed video game. I don't particularly enjoy puzzle games but Portal is one of the most elegantly-designed and engaging games I've ever played. When a studio designs a good game, the genre doesn't really matter; people will play it because it's a good game.