Really. The core of the development is great but missing a plugin manager. Having ability to add custom plugin modules without having to deal with the engine source would be a very apperciated. This would allow one to customize the engine to their own liking. If they want a feature such as speedtree/ngplant one can just plug in that feature.

I know this is probably available the pro release but it should be in all since I personally don't want to recompile the engine just add a feature.

I would also love such a feature...
However, I don't think that it will be implemented, because it's in the pro license and you can do most of the stuff with a little "workaround".
Nevertheless I'd appreciate to see this feature at least in the "For Hobbyists and Enthusiasts" version of the engine.