Back when Stack Overflow was first started, the Community Wiki feature that was initially created to add a wiki-like aspect to some questions was co-opted for use with poll-like questions, and questions where it didn't make sense for the author to receive reputation from them.
I've always liked these questions and felt them to be an important part of building and maintaining a healthy community here, but I do agree that, if left unchecked, the site would quickly fill up with people abusing them. However, I think that we've maintained a pretty good balance here on Ask Different - we don't allow too many to be created, and the ones that are usually are informative and maintained. There are some that do fall through the cracks, sure, but I think that by and large they're more beneficial than detrimental.
One example of a benefit is with the recent What tiny thing in Lion makes you smile or caught you off guard? question, it was linked to on Reddit, Hacker News, and Twitter, and several other sites and brought a considerable amount of traffic to our site. This is very hard to do with a 'typical' question because they're usually of limited scope and of interest to a relatively small group of people. In order to get the network effect with a question, it needs to be one with a much broader appeal, and these tend to skew towards those that are of the Community Wiki style.
Finally, I think that the popularity of these questions may make it appear that there are more of them than there are, so here are some numbers:
- Total number of questions: 6,778
- Number of Community Wiki questions: 73 (1%)
- Number of Community Wiki questions with at least 1K views: 12 (0.2%)
- Number of Community Wiki questions with at least 10 votes: 17 (0.25%)
- Number of Community Wiki questions with at least 10 answers: 23 (0.3%)
So yes, I will concede that the questions, in general, don't really fit in with the rest of the site. But for the ones we do have we try to keep the quality high and the quantity low, and I think that eliminating them altogether would be a mistake.