I'm not sure if anyone has ever noted this, but when Epic added their in game purchase option the prices was $7.99, while the price through Apple was $9.99. However, if you take off the 30% cut that Apple takes off of a $9.99 purchase, you get $7.69, which means Epic was charging people $0.30 more than they would have received if the purchase went through Apple. It's a minor thing, but it's a bit of a fail on their part if they want to argue they are doing this on principle.
The judge probably has the right of it...punishing everyone who depends on the Unreal engine is not fair to everyone else, but Epic deserves what they are getting because they made their bed. Apple needs to support the App Store and iOS infrastructure that all these apps depend on, so the developers should be paying something to be on the platform (just like they do with all the other ones). Whether it's 30% or some other number is a separate question, but Epic's idea that they can live off of Apple without supporting the infrastructure they are using to make their money sure doesn't seem like anything but pure greed to me. It would be far better if they were honestly negotiating for a different pay structure, or that features come with a higher charge...say, if you don't use in app purchasing then you lose the support for all the things that go with it but also don't have to pay Apple x% for that support. Just getting it all for free makes no business sense for Apple.