Dusan Writer wrote a really interesting piece about the direction that the Lindens seem to be taking SL: integrating it into our offworld-but-still-digital real lives. I find this direction really worrying, because I do not wish to have my lives commingled in this way. There are some people offworld whom I tell about my time in SL, just as there are some people inworld who have also met my meat avatar, but that's as far as it goes. Right now, I control who knows what about me, and I wish it to stay that way. The Lindens' new plan feels like it will take that out of my hands.
Augmentationism is one of a set of words describing people's opinions (or opinion-driven actions) about what SL is for. Augmentationists believe that so-called real life is the only valid reality, that anything that happens outside of RL cannot possibly be other than a more-or-less meretricious form of entertainment. Hence they believe that SL exists to enrich and enhance our offworld lives. They believe that SL has no separate existence, no culture of its own, and no community.
I suppose there's no reason why an augmentationist could not have a differently-gendered avatar or be another species, but those whom I have met tend to believe that these things are false, morally wrong. Some even reproduce their RL appearance in their avatar (though these too are often suspiciously tall and fit and beautiful).
(The opposite of augmentationism is immersionism, but that's a subject for another day.)