[Xinhuan]

That's the thing. The setting up of wowace and wowinterface were huge factors that allowed WoW addon programming in general to flourish, to have a forum of discussion. In particular, I want to mention the WowAceUpdater (WAU), it made addon updating so easy that much more users were willing to try out modding. That and the fact addon hosting sites went up, caused addons to be used widespread.

"A golden age is often ascribed to the years immediately following some technological innovation. It is during this time that writers and artists ply their skills to this new medium."

It wasn't just about "new and groundbreaking addons", it is also about the technology and other factors that made it possible.