…But what are the alternatives, really?
If they allow you to ship with the UE4 editor, you’re shipping them everything we’ve paid for for free. Who would buy unreal then? Nobody, they’d buy a game and get into it that way. This would also come back on you, because as a developer your customers would hold you responsible for everything you ship with the game. What if you ship the game while the engine has a severe bug that gets hotfixed a few weeks later?
The other option is an in-built editor of you’re own, and you’re right, shipping with UE4 could get pretty overwhelming for the average modder. But this way you’re in complete control.