I would agree that the three questions above are examples of the type of question that should be closed due to being too elementary.
Having said that, I would like to argue that the scope of allowable questions should be kept fairly broad. As someone who hasn't done graduate coursework in TCS, I find the CW/big-list questions very helpful. (My own question had 4 votes to close before anyone had a chance to reply, but I think it turned out to be useful to others.) I know that you don't want the mix of questions to become too elementary and put off the serious researchers. It would be nice to be able to segregate the more basic questions from the advanced, but given that the theory community is small, there probably aren't enough people to support two separate StackExchange sites. And hopefully some of the people asking basic questions will eventually be asking (and answering) more advanced stuff.
Here's one little idea that might be workable: ask that anyone posting a question that could be considered undergrad-level material to tag it with something like "intro". Then anyone who doesn't want that stuff cluttering up their view could add the intro tag to their ignore filter.
I think over time the mix of questions is going to include more like Jeff Erickson's, and this will become a less sensitive issue. (By the way, has Bill Gasarch visited here yet? He's posted some questions in the past on the CC blog that would be great for this site.)