Well -- my guess is that answers which many people can understand and verify quickly are upvoted more likely in general. Unless they are too easy, of course.

@MichaelAlbanese: Thanks. -- I have done so. Let's see whether the answerer gets back to it before MO runs out of patience ... .

@quid: Ugh ... . I'd say it's not so different, but I really don't see why there are THAT many upvotes on such question and an answer which probably almost everyone of us could have given.

@FrançoisG.Dorais: I'd say this is not the right question. -- I just think that if one plans something which may well be nonnegligible work, it is usually good first to think about what purpose(s) the outcome should mainly serve.

What is the intended purpose of such 'success stories' list? -- Is it mainly for our own bookkeeping, should it make MO more attractive for its visitors and potential future users, or should it help with fundraising for the site -- or what combination of these or what else?

@quid Apparently Manfred Weis has already asked that question in March: mathoverflow.net/questions/124089/… . It is still open, though -- I think understandably -- it has not yielded much feedback.

Unfortunately, most questions on MO of the type of which quid says it is to be avoided are really of so poor quality that one cannot do much else than closing and deleting them. Nevertheless I am not convinced that questions asking for what some work might be relevant for, or whether people think for the one or the other reason that it might be more or less interesting should be banned in general. -- Although partly opinion-based, questions of this type are important in mathematics as well!

As the other commenters have already suggested, a request for an overview would be perceived as too broad. In general asking answerers to write something similar to a Wikipedia article is not welcomed on MO. On the other hand, of course you can ask e.g. for the present state of things with respect to a particular problem.

I think voting up or down questions influences the scope of the site in a similar fashion as votes to close or reopen a question. Thus I think letting new users vote quickly may be problematic for the site. Also, voting is not really necessary for using the site in terms of asking and answering questions and leaving comments. It is rather a means to help maintaining a certain standard, and to provide feedback on what colleagues think about a particular question or answer. Both purposes are served the better the more knowledgable voters are on average.