That's actually something I do do! One of my on-again, off-again projects, which now that you mentioned it I should return to, is going through the book American Women Historians, 1700s–1900s: A Biographical Dictionary, and adding articles on the ones that're missing (which is a lot of them), especially those where I can find 2-3 additional sources to use for an article (which is still a lot of them). So far nobody's tried to delete my contributions.

There are also some more organized projects. There are a few dozen people at WikiProject Women's History: http://en.wikipedia.org/wiki/Wikipedia:WikiProject_Women%27s..., and Wikimedia hired a paid Community Fellow to focus on gender-gap issues: http://en.wikipedia.org/wiki/User:SarahStierch