Human nature. They built part of their identity on the historical stories.

[saras]

Lots of good discussion of the subject, although all 15 years old, at http://amasci.com/weird/wclose.html, Bill Beaty's weird science site.

Aside from that, in the non-academic world, "revisionism" has bad connotations. It implies deliberate deception and the rewriting of history for partisan purposes. It generally does not, except in the academic world, imply the correction of biased or incorrect history.