I don't know why they have never supported mods for Diablo, while Starcraft and Warcraft get all sorts of fanmade love.
On the bright side though, Torchlight 2 is coming out in April 2011 (i think) and it sports the dev tools and LAN/Peer-to-Peer Co-op support.
I suppose, with enough effort, someone could recreate Diablo I, II, or III within Torchlight II adding any mods they wanted to the game.
The dev tools from Torchlight I were very very good and will most certainly be improved upon.








