I don't know how the walls and levels were designed, but if there would be a away to change it...like different "skins" to make your farming everywhere, and maybe even have map options? ...kinda like Starcract. So you could make the fields of misery level much larger, or have incentives, but maybe change it to dirt, mud, grass, or volcanic ash. (rough example, lol)

Implement a level system. Make it more mazey like D2?

Then you could invite your friends and level in other people's settings, however that user has their skins setup.

I really miss some of the D1 and D2 level designs. I'd love to see D3 do it all. :)