Blizzard’s plan for modding is to create an online shop where people can sell their mods. Allowing mods created problem where players were using the game engine to create different forms of gameplay, use Battle Net and Blizzard customers for testing purposes, and then move the mod OFF THE PLATFORM to where they could get money. Tower Defense and Defense of the Ancients, both of which originated with Warcraft 3, had this problem. Blizzard’s response is to allow people to sell their creations within Blizzars’s structure which, they hope, would remove the need for the mods to move off the platform.
How did Warcraft 3 get so heavy into modding? It started out with the general map editor of Warcraft 2 and Starcraft and people kept tweaking the engine more and more.
I’m actually curious how Diablo 3 maps are made. Since some parts of it are randomized, there is clearly a ‘cut and paste’ element for some elements. Perhaps it would be in Blizzard’s best interest to introduce new maps, not unlike what they do for Starcraft 2, to remove the repitition. For example, why not add some more maps for Act IV since it is so short? Those maps could only be unlocked once you finish Act IV.