Well, I think they´ve got some well paying sponsors + many sold copies = much money -> nice features -> even more sold copies -> ...

I am not yet much into unity but will get more into it soon. So far, I like gamestudio a lot for its flexibility, by still being easy to understand and very comfortable in terms of coding most things.

However, those seem to be some nice features if one wants to create a modern game without having to care about the tech.
On the other hand, Unity costs MUCH more than gamestudio if you want to be able to have the same features...