I wouldn’t. Certainly not without official mod tools like Warcraft 3’s map editor.
But if it were officially supported? …I’m with Bovie. Hell, I’d go a step further and try to make the entirety of Sanctuary for Adventure Mode so you can free-roam at your leisure and just explore.
…But that kind of gameplay doesn’t lend itself to what Diablo 3 is, either, so… no, I don’t think I’d mod Diablo 3.
Wow, you must be fun at parties.
Modding is not cancer; it is actually the only thing that keeps GOOD games alive and relevant no matter what their age.