Best explanation I have heard yet is that the original BC was changed to "Barry Soetoro" (and maybe even shows him being born in Indonesia) so that he could get admitted to schools as a foreigner. I do believe he was born in Hawaii (you can't explain the newspaper announcements any other way). Having the wrong name on the BC and any other subsequent docs (like admissions papers) would be more than a little embarrassing and, as noted above, his grades would finally receive the scrutiny that they deserve.
Wouldn't it be interesting if BO's grades were not as good as GWB's?