I understand that some of the information might not be reliable but, at least from my experience, most of the information you get from Wikipedia is general information readily available on other websites, and thus easy to fact check if necessary. I also feel that Wikipedia is typically used as a starting off point if you have no idea what your topic is about. So if you are just using it for general background information referenced later in your paper, why can't you use it? I feel as though students should be able to use is as a source as long as the information cited is supported by later facts. Obviously if the student pulls a fact from Wikipedia that has no logical backing and therefore contradicted later in the paper, the student deserves to get points deducted for not checking his or her facts. However, if you pull a date from Wikipedia that is supported on other websites and follows along the timeline you are referencing then you should be able to use it. I am not advising people to use Wikipedia as the go-to cite for major, extremely important, specific details. However, as an outline or general reference guide, I believe it is a fine starting point.
Did you know that there are few female editors on Wikipedia and they are trying to attract new Wikipedians?

Wikipedia editors met in Berlin