Thank you for your support. =)
Yes, the concerns about big worlds are right. I didn't put any pictures up that show how these worlds look like and how strict they're being limited (at least later on, they will have a limitation depending on the Steem Power of the user), which is also a reason why people might think that entire Minecraft worlds are meant. While the world size can be changed, it will have a limitation at some point how big it can get.
The changeable world size is going to allow builders to create worlds that will form the base on which they can build their hubs, that then can lead to their creations, like custom made jump and runs or adventures maps. The world creation part is purely targeted at the creative part of the game for the building and saving, as there is no layer that is checking for cheaters.
Of course, building bigger and fancier custom worlds will increase the size, but these worlds will also add value to Steem at the end and still have a size limitation to prevent someone making too big worlds. :)