hm -- us: non-standard does not imply a negative judgment - it means exactly what it means. And when it is used to mean "plural of you" (and not "all of you"), it IS non-standard.
Ffive - I have heard women use that to other women, even in Louisiana.
As to "sexist language" - the problem is that most people simply do not care. My boss is an old-school feminist and insists on "he" being the form used in ambiguity because she hates the idea of people deliberately meddling in the language on behalf of people who never asked for it. Then you also deal with the fact that a lot of women are just fine with traditional gender roles and see no urgency in breaking them down, nor feel offended or oppressed. To dismiss them all as ignorant rednecks would be rash.
The intentions are good, I know, but as far as "Fortunately, eventually more and more people thought about it and came to change their minds, or at least their practice, because they started to realize how it could come across" ... I think it was that more people either caved to political pressure or got so tired of hearing about it that they used the new form - forms which I, among others, hate because they were invented for purely political reasons and did not develop from the ground up.
ALL of the new "gender-neutral" forms are poetically ugly, in my opinion, and "he or she" is a disaster (and I use it often, believe me - mainly out of fear).
And "man" DID historically mean something closer to "person" and only later took on its exclusively male meaning. I see nothing wrong with "mankind" - for jobs and stuff, obviously calling a female a "chairman" or a "policeman" is wrong. But I'm still gonna say "mailman" unless I know it's a woman, in which case I don't know what to say - letter carrier is so artificial to my ears :) Should we purge all our stock phrases and compounds like "Fall of Man," "manslaughter," "manhandle," "brotherhood of man" (siblinghood of humanity?), etc?
As far as "you guys" - I think it has lost any and all gender connotations that the word "guy" alone has, and the fact that you mention people would not say "you men" or "you boys" proves that - no one balks at "you guys." Things can change that way, too.
NOT trying to get in another fight, btw, just wanted to offer another perspective! And I still hate "you guys," just for different reasons!