The UI for sports is currently terrible, by and large. The best you can do - despite the fact that everyone has a computer attached to and/or in their TV these days - is stream a linear broadcast channel. With this deal, Apple can show you a dashboard of all the games currently playing so you can pick a close and/or intresting one. You could choose a different audio channel - say, crowd noise only or a mic attempting to pick up what a manager is shouting at their players. Picture and picture if a goal is scored in another game. Probably way more than all of this.
From this POV, buying content is merely the price of admission to using technology to completely change and improve the sports viewing experience. Like I said, I'm just guessing at what Apple is thinking, but it stands to reason they have some technology angle on this if they feel like they are the right people to mount an attempt at improving this experience.