i did not mention monsters and people walking up slopes or campfires because both games can do that. and the foraging/mining isnt the same. take away the landscape and the plants and ore remain. they are seperate. and i cant think of anything city limits does except open up a new chat.
going from 2D to 3D will crash the game. you would have to add physics, jumping, make everything have z-axis as well, and then there is going to be colliding problems because Wurm uses item models where as in WoW the only thing you see of an item is a picture.
... I'm completely stumped. You're just doing this on purpose, are you?
WoW has 3D models all over the place, like houses and rocks, you can collide with. That's no different at all from rendering items dropped on the floor. Wow just doesn't do that because it's a lot easier for the player to loot the monster itself, and it saves on 3D models which would make the game client (the bit you download or buy) too big.
You didn't mention slopes and compfires because both games can do that? Bravo, because that's exactly what I wanted to point out. Both games already do it, and the code they used to do it is the same kind of code needed for almost everything Wurm does, thereby proving that a Wurm with WoW graphics and an extra axis would work!
Wurm does not have jumping simply because players wouldn't be able to bypass player-built fences easily, which is important in Wurm.
City limits may not do much more than open up chat, but that's completely besides the point. It's still code that checkes the player's location versus an area on the terrain. Same code, same strain, different application.
Ores and plants? Sure, WoW has them in separate models, but the code behind them isn't any different than in Wurm, Wurm just has it tied to the tile itself. The fact that there's thousands more tiles in Wurm than plants and ore veins in WoW doesn't make any difference in code or strain at all.
Seriously, go do those game-development courses again, and learn that there is a huge difference between what you can see and the code behind it.