I can fully agree with that one. I mean, I'm not saying they should copy specific locations from those mods, but I hope that Skyrim can pull off the uniqueness and viersity that Unique Landscapes brings to Cyrodiil. And I hope to see the level of detail and variety that Better Cities brought to the game's cities as well.
Also, I hope that Bethesda takes inspiration from the "Harvest" mods as well. These mods both add to the realism of the game and make it easy to see which plants you've harvested and which containers you've opened. Though admitably, in Fallout 3, the Point Lookout DLC already incorporated similar behavior to Harvest Flora for the punga fruit it added, and New Vegas also applied this to the various harvestable plants in it, I also seem to recall that some containers had animations which showed them opening, but not all of them, also, they would automatically close once you exited the container screen, and the game would instead use the less graceful method of adding the word "Empty" under the container's name to tell you which one you'd looted, and it only applied to containers that were empty, if you did not take every item in a container, there would be nothing to indicate if it was empty or not.
And if the game still has buildings handled as interiors seperate from the exterior world space, then I hope they can have something similar to the Natural Interiors component of All Natural, best if they can do something similar to Immersive Interiors as well, I want to at least be able to hear the weather sound effects when I'm inside buildings. And hopefully, for exteriors, we'll get something like the various window glow type mods.
Finally, we really need to have the functionality of Real Likes and Darker Dungeons incorporated into the game by default, I should not be able to see clearly in a dungeon with no windows or openings to the surface in sight and no torches or other sources of light nearby, torches, or nighteye or light for the more magically inclined, should be a necessity, not decoration like they are in Oblivion. To go along with this, I want to be able to drop lit torches during combat, similar to the Oblivion mod, to avoid getting something like Doom 3 where you're constantly needing to put your light away to fight monsters and then not being able to see them as a result.
For some more gameplay oriented mods, I'd agree that some large scale overhauls like OOO would be a good place to look for inspiration. Bethesda doesn't need to add all the specific enemies or items these mods have, but some of the design concepts that help to make them as popular as they are could work well as part of the default gameplay of Skyrim. I'd also say Persuasion Overhaul, or a similar mod, because I hated Oblivion's default persuasion minigame. Mods like Deadly Reflex could provide some good ideas Bethesda could use for enhancing the combat system too, I also hope Bethesda takes a look at some of the popular magic overhauls for Oblivion, because both Morrowind and Oblivion failed to do magic justice, I've always felt, and pure mages just felt kind of underpowered to me.
I was a fan of the Oblivion mod Alive Waters. I hated the fact that when you go in the water that there was next to no life there. Also, Darn's UI is needed, what we are provided with is absolutely horrendous to look at.
I can agree with this here as well, if you're going to let us explore under water, then you should add some things down there, even if it's only cosmetic. Lake Mead in Fallout New Vegas felt like it had more life than Cyrodiil's water's, honestly, and we're talking about a post apocalyptic game here. And I hope that this time around those of us who play on the PC can get an interface that actually works well on the PC version. I mean, I know that the console versions need an interface appropriate for consoles, but surely it isn't that unrealistic to ask for a different interface on the PC version?