Amazon have free SpeedTree modeler for Lumberyard

No you don’t.

That’s poor example. You just as well can end up with bad tree by modeling it manually, you just waste 10x times more time on doing it.
You can just as well create optimized tree using SpeedTree. You are just cutting yourself from very powerfull, specialized tool, which when used properly will always deliver better and quicker results than modeling by hand.

It’s like telling than modeling clothes in ZBrush+Maya is better than using Marvelous Designer. It’s just ridiculous. You will get better results in specialized tools, you just have to learn them first.

Either way SpeedTree 8 will be available for Unreal.