fps templates similar to some of 's where you can drag and drop models/materials and use the animations provided very easily, one in particular is called ufps: ultimate FPSwww.assetstore.unity3d./en/#!/content/2943, that would be incredible to see in UE4.
Also just user content in general would be nice to see. Maybe blueprints where people just ask for donations since they can easily be copied.
Really just anything to make the main type of games people tend to make a lot easier and quicker.