Personally, I am not comfortable with the idea of mitzva tanz. Why would I want all the men standnig around and watching me "dance?" yichers
I think you're right. (but only if you're referring to the non-observant kind of MO, that is) The "Modern Orthodox" group "Edah" seems to be currently organizing itself around a hashkafah that's virtually indistinguishable from what Conservative Judaism started out as. I call it "Conservative Judaism: Take 2". The guiding philosophical principle for both groups is what we call "positive historicism". This term comes out of the German philosophy of the 19th century (e.g. Hegel) and is just a fancy way of saying "human morality and wisdom are progressively improving" and is exactly the opposite of yeridas ha-doros. For example, Edah advocates women having aliyos because of the "progress" of feminism.
but it seems that the Conservative movement started out kind of how Modern Orthodoxy is now.
One big difference, in my opinion, between early Conservative Judaism and Edah is that the early Conservatives (e.g. Zechariah Frankel) explicitly said "we are historical positivists", whereas Edah doesn't openly explain that this is what is driving them. The Edah people just assume that positive historicism is obvious, or aren't self-aware enough to realize. Or maybe, (now this is cynical) they just don't want to say it out loud because they don't want to be seen for what they're all about.
At first glance, I think some of the back-and-forth on this thread centers on terminology. When TRA says "Modern Orthodox", he is sometimes referring to people who aren't really committed to halacha, people that Opus prefers to call "Modern Orthodox lite".