The dimension itself has so much potential, I commonly see complaints about it not offering much.

• Trees should have their own saplings and the wood planks should have their intended block variants (e.g. fences, fence gates, doors, stairs, slabs, etc). Maybe shiny particles come out of the leaves too?
• More islands should spawn in the dimension, similar to the original Sky dimension idea back in beta or the Aether. Just having one giant floating island like the old End is pretty boring to have for it.
• The Ogre Lair blocks should all be rehashed for an extra biome you can find in the dimension, an amber forest type biome perhaps?
• Better ways to enter and exit the dimension. The staff should only teleport you after charging it for a few seconds (like a bow) and when using it on a specific portal block. Teleporting out of the Wyvern Lair should be possible anywhere instead of the specific position where the quartz structure is.
• A simple caves system to explore (though not much point of this when there's no new ores yet). New materials to find would be cool too instead of utilizing on only vanilla items for some of the more expensive Mo' Creatures items.
• Small dungeons to encounter with a few mobs like wraiths or silver skeletons guarding loot.

Not really needed anymore because a rework is already in progress for the next couple of updates.