Some good news about lighting in upcoming UE 4.16.
Epics has optimized DFAO, so it might return in squad in later releases.
If you dont know what DFAO is, here is the link.
Also I should say that lighting in open world games made on UE - is one of the major problems in my opinion.
The second problem (and the most important) is perfomance and the absence of primitive methods of optimizing ordinary things, such as the absence of shadow lods. Yes, you can do shadow lods using blueprins (prefabs), but from the engine like UE4 I personally expected something built-in inside mesh import pipleline, the same way such as ordinary lods import for example.
Also the overdraw budget is really low.