The problem with your example is that Math Overflow is not a Stack Exchange site. That is, it's not run by the same people who run the other sites on the Stack Exchange network. It is a relic of an earlier failed venture, now known as "Stack Exchange 1.0", where our Q&A technology was licensed to other people who wanted to run sites in the style of Stack Exchange sites, but promised to do so without any official ties to Stack Exchange or any of the other sites on its network.
Math Overflow is run by a completely different set of people, and not subject to any of the same rules or community norms that the Stack Exchange 2.0 sites (those are sites like this one, created through the new process on Area 51) follow.
On official Stack Exchange sites, we've found through trial and error that "big list"-style questions just don't work. They are not a good fit on a focused question and answer site. Yes, they are very popular with the community, but they have a very real broken windows effect that we simply can't afford to allow.
The FAQ does cover this explicitly where it lays out the types of questions one should not ask:
To prevent your question from being flagged and possibly removed, avoid asking subjective questions where …
- every answer is equally valid: “What’s your favorite _____________ ?”
- your answer is provided along with the question, and you expect more answers: “I use _____________ for _____________ , what do you use?”
- there is no actual problem to be solved: “I’m curious if other people feel like I do.”
- we are being asked an open-ended, hypothetical question: “What if _____________ happened?”
- it is a rant disguised as a question: “_____________ sucks, am I right?”
Your proposed question ("experiments in cognitive science that every philosopher ought to know") falls into at least 2 or 3 of the above categories. Even if every answer to that question isn't equally valid, it would be very difficult to come to a consensus on which experiments actually are those that every philosopher should know about. That teeters quickly over into "extended discussion" territory, which is something that we try very hard to avoid. If the question sounds more like a "poll" than a question, then it is not a good fit for our site.
I said before that I don't think there's anything wrong with the previous specific question that you asked. If you have more questions of this nature, then I encourage you to ask them. Try to make sure that they're grounded as much as possible in the study of philosophy, and if they're not, one of the moderators (or other experienced community members) will do their best to try and help you reformulate the question.
But what you propose is not a good solution, even if it were to bring more traffic, because it is not the type of traffic that we wish to encourage.