Since history is so often employed for political purposes ("It is a principle that shines impartially on the just and unjust that once you have a point of view, all history will back you up"), it's not surprising we don't discuss it much. If, even with this disfavoring, people still think posts like http://lesswrong.com/lw/cuk/progress/ are worth posting and inspiring pseudohistory like this - then this is not a disfavoring I can disfavor.
Not that excluding one area is much evidence of insularity. If one declares one will eat only non-apples, is one an insular and picky eater?
I absolutely agree that history is filled with politically motivated bias. But there are actual historical facts (someone won the Siege of Vienna of 1529, and it wasn't the Ottoman Empire). There are historical theories that actually fit most of the facts and pseudo-historical theories that fit carefully selected sets of facts. Being able to tell the difference is a valuable skill that members of this community should try to develop.
To put it differently, the falsity of the theory of moral progress has implications for assessing the difficulty of building a Friendly AI, doesn't it?
If it's worth saying, but not worth its own post, even in Discussion, it goes here.