Great to hear that from you, ! 
I am developing a RTS game, and I think you know most RTS really depend on maps made by the community. If Epic could offer a “default” Map maker which is customizable by the developer to fit the specific needs, that would be awesome.
For example I would not want people to be able to use any blueprint stuff, I just want people to be able to create their own landscapes (sculpt and paint), place predefined actors (buildings, trees), set stuff like mission target or mission description, and then safe it and upload it somewhere. And I would want to create my own UI for that.
Other developers may want to allow blueprint scripts or the import of custom meshes, but should all be possible to disable/enable by the developer.