ReflectionCapture actors are not going to be feasible in dynamic scenes (other than trivially small ones), the rendering overhead is just too much. It’s even worse with dynamic lighting and shadowing, we would have to re-render shadowmaps many times. Each reflectioncapture needs 6 renders of the scene, so for just 10 captures we’re talking 60x more rendering thread cost than rendering the scene normally. We could optimize that to render the cubemap in one pass, but that would still be 10x more rendering thread cost. There are really 2 or 3 feasible realtime reflection methods that I’m aware of, these are all distinct features from the existing Reflection Environment.
Ease of use is important to us, but it’s always a tradeoff with quality and performance. Fundamentally we’re trying to cover all the bases and let each project choose how to make that tradeoff. That flexibility to choose is important for an engine in which you can make many types of games, which UE4 is designed to be. You can use fully static (mobile), partially static (highest quality and perf), fully dynamic (lowest perf, currently missing some important features). We’ll continue to improve the fully dynamic lighting path going forward.