I hate to be the bearer of bad new but...don't bring a sh*t game into a decent one.
Sh*t game? Minecraft is a lot of fun. It looks like sh*t when you take a first glance at it. But I will say, its one of those games that is simple, but gets addicting.
The game is a LOT more fun when you play it with other people.
Edit: I built a good city in the game if you want it. Just give me credit. Also you should do some well known MC builds to include:
-Empirepolis (Large american city.)
-Enterprise D 1:1 scale (place up in sky, way above map so you cant see LC from it, and you cant see it from LC)
-Disney World (Yup, someone actually made Disney World in MC)
For the cities, people have used slabs for ramps. Those could be changed to a slope with that texture, just because, we all know that a car on GTA isn't going to be able to drive up those.
Though I agree, seeing MC maps on GTA 4, and not being able to build or place blocks does feel kinda silly, but its a neat thing to just mess around in for a little bit.