I think a level editor/creator in dark souls 2 would be an excellent addition. Basically, we'd get a blank canvas, and get building blocks from the other levels, as well as enemy spawn points and bonfire placing, and just get to create our own dark souls map! This would probably be best as a PC only feature just so that it would not be held back by consoles. It could work where you could post your map you made onto a forum, and then people could up-vote it or down-vote it, so when browsing through for new levels to try, one could either look through newest, or top rated, and download it onto their game to try.
Some may say this is a bad Idea because it would distract from the main game. This is true, although it would also keep people involved in the game far longer than they would with just the official map. Why? Simply because there would always be new content to explore!
Some may also say that people would abuse the system and just make an area with 20 silver knight archers, or just some impossible unbeatable level. That is what the rating system would be for, and the comments.