A couple of days I did some thinking about the trees.

Yes, to me from a distance a forrest seems darker that what we have ingame. However, when I imagine a tree whose leaves do have the dark green that I imagine for a forest it just would not look right. I compared this recently to the trees I saw when taking my car over 500 km. And indeed the trees don't look dark at all when looking at them individually.

I then came to think that forest just seems to be so much darker than the surrounding meadows because of shadow. In fact the totality of leaves of a tree represent a much more fractal shape than meadows (that's the evolutionary benefit of leaves on a tree) and thus there's more fractal shadow on the inner layers of the tree crown. Hence why they appear darker from the distance while on close up they aren't.