This is what we saw until now when any game tried to do it. But I keep hope that one day, one will do it in a good way (but I still wonder what way this is ).
There's a huge limit to what developers can create, while a community has virtually unlimited options. I'm pretty sure the "good way" to do this would in fact involve even more work on Blizzard side than currently (well, mostly validating / testing / idontknowwhating).
What I'd like to see is a game that doesn't involve players in content creation just to be lazy, but to offer real expandable (and quality) content, and that's where all the challenge is.