This is not the most relevant tradeoff. The United App is the only way to watch in-flight entertainment on many United Flights (esp. on newer planes without seatback screens). Every time I fly United, they make an announcement that says "Make sure to download the app before we take off because you can't do it once we're in the air!" and then I see everyone whip out their phones and tablets. Usually that's 10m or so before we lose cell reception and it's often not enough time to fully download the app.

I've often thought that they either need to cache the app locally on the plane itself or provide a special free passthrough on the in-flight wifi, but so far they haven't provided either. In any case, app size is crucially important for the key use case that many (most?) people use the United App.