There's been 0 world building in the reboot. There's been little explanations of things and everything just gets dropped on us and the explanation is usually (and I'm going the cinema sins route on this) "Because.... reasons"
The same can be said for the old continuity and even SatAM itself. The series dumps you in the middle of the conflict without any given explanation until much later; and even then, it still doesn't address everything. Robotnik took control of Mobotropolis because... reasons; he wants to roboticize everyone because... reasons, yet he banished the king because... reasons, and is fighting a blue hedgehog that runs super fast because... reasons.
The comics and show started out the same way and, as time passed, everyone became familiar and grew attached to it. But now since that's all out the window, they have to do it all over again. And so far, they've introduced a whole lot of new material to work with. There hasn't been much development because they're not done introducing everything yet.