Sorry, what? If someone told you Wikipedia succeeded in a "fight for legitimacy", you were lied to.
they're just tools of the giant corporate publishers
You don't have to be published by giant corporate publishers to be cited on Wikipedia. You don't have be published by corporate publishers, giant or not. There are an immense number of citations on Wikipedia that fail to meet those criteria, and they can even be the best sources to cite (and not just because of a lack of sources).
Instead, they would need to recognize Lulu (like Amazon and the Library of Congress do) and accept books from there or be shown as complete hypocrites.
No, no; no need to argue here. You already had me sold. Down with nuanced understanding, I say.
A "nuanced understanding" of rules just lets people enforce them arbitrarily. Either make them concrete and fair, or find a way to not need them.
http://deletionpedia.dbatley.com/w/index.php?title=Special:R...
Another thing to note: People say that Lulu doesn't have an editorial process but they do. Once you publish a book they review it and if it meets their standards they put it into Amazon and other sellers for you. Considering that editorial standards at all publishing houses is damn near zero except for copy-editing and slapping a cover on, I think it's fair to say Lulu is just fine as a source.