Id just like to chime in, if these are known weaknesses of UE4 as you say and Cryengine better supports the feature set you require then I think its a mature perspective to consider moving to an engine which may cause you the least resistance. Obviously these issues can be alleviated in UE4 but the skill of the person making the scene is heavily in question not only the renderer, to jump on the renderer first is really not the best approach in my opinion. Its not that youre entirely wrong, its the way people around these forums expect Epic to do their work for them, obviously Id like the renderer to be as fast an general purpose as possible but Cryengine was built with foliage in mind since it was used for Crysis so thats a specific set which may always outperform a general purpose solution.
Granted not everyone uses the correct tone in putting things across but there are a hugely varying bunch of age groups and skill levels, its extremely difficult to come to a conclusion from acouple of lines especially when discussing something as complex as a renderer, you have to admit you hugely jumped the gun with your blanket statement about optimization.