GTA is a whole different beast altogether. Yea it is huge, but take into account that each and every building is not explorable, and the side quests if you can call them that are not as lengthy, there's not locations upon locations that you can actually go into and explore, etc. In other words, they have a lot less actual content in their game. Most of the game is just main quest and graphics. So they have a lot less to worry about when talking about things like loading up new areas quickly and what not. Basically, if they made Skyrim like GTA, the actual land would be a lot less detailed (talking explorable areas like dungeons and caves, not graphics), and not filled with nearly as much content. All for the sake of adding fully controlled dragons.
GTA 5 is gonna be as detailed if not more as Skyrim. Plus the map is gonna be 3 GTA maps put together.
