SJ:
I'm not sure that intense game-playing on the wiki is a great thing. And we can all imagine marginal ways in which doing anything but concretely building the encyclopedia -- editing one's own user page, adding to BJAODN, fooling around with personal CSS or javascript settings, chatting with friends about non-encyclopedic subjects -- is 'wasteful'.
None of these activities are perfomed exclusively by members of the community. (In the case of BJAODN, it's also a useful service, because the people posting stuff to BJAODN are frequently the same who are vetting out the nonsense in the first place. BJAODN also reduces trolling about censorship.) If they are, as in the case of people abusing their user pages as webspace, we generally don't tolerate it.
The issue is that games can exist entirely in parallel to encyclopedia-building. For example, the user who created the "Wikipedia:Wikigames" project (since redirected) has never made a single edit to a Wikipedia article. When the fun activity becomes the primary focus and the encyclopedia becomes incidental, a line has to be drawn.
That's why I believe, as I have posted earlier, that any fun or game activity has to meet a rather high threshold of community approval. If games have to be started in the Wikipedia: namespace, instead of the Sandbox as currently happens frequently, I think things will evolve naturally into that direction.
Surely banning all "fun" from Wikipedia would be an overreaction. But this is not going to happen. As is often the case on wikis, things tend to escalate beyond a certain level of tolerance, the group who was previously a minority suddenly becomes a majority, and the measures advocated become more drastic. Hopefully this will lead to a mutually acceptable solution in the end.
Erik