So I went to the realms in creative and looked around. I gotta say they are unique. That said, they are really barren. Is there any plans to add dungeons or villages or something else to each of the realms? Sure they look neat, but there isn't really much to them. For example, the deeplands is pretty lacking in anything from what I could see. Sure there is a few ores here and there and a few mobs, but that is about it.
Maybe try adding some dungeons, unique treasures and possible some friendly npc villages to the areas. Maybe a few unique companions in each realm to recruit and have them like friendly npcs you can take home and have live with you or something. Just anything to really liven up the realms and give some deep meaning to going there.