Wikigroaning is funny and/or embarrassing depending on your outlook, but is it a problem? I agree that the serious articles should be better, but in these comparisons there seems to be an implicit theory that the fan topics are somehow sucking the life out of the serious ones.
But really, do we want somebody obsessed about [[Optimus Prime]] to spend a lot of time on [[Prime number]]? And even if we wanted them to, would they do it and do it well? I don't think so.
From what I've seen, the fan stuff is not a particularly big maintenance burden. Maybe I've missed it, but I don't see a lot of vandalism, a lot of dispute resolution, or a lot of AN/I requests over the stuff. So it seems like the net cost of keeping it is relatively small. And I see two big benefits that come from it.
First is that the more editors we have involved in Wikipedia, the better. People identify with things they've contributed to. That gives us all sorts of positive effects, including less vandalism, more donations, more person-to-person promotion, and more public support.
–William Pietri, on the mailing list