I honestly don't get why people think that if the MC turned out to be Burg that it would be such a terrible thing.
If this letter has anything to do with him discovering who is mother's family are, it doesn't carry as much weight for the story if he turns out to be from a rich family that we don't know about, even if they are, in this fictional world, considered to be a more prestigious family then the Bs and Rs. Whilst he does still gain a link to a (presumably) prestigious family and possibly access to money, gaining the name of Burgmeister has a far greater impact because of its, and by extension his, link to the college as well as to certain other characters. The implications of this revelation would also have far greater resonance than if he were from some other random high society family, because it's all well and good that he's from that family, but being from a family so closely linked to the story is much more relevant.
DPC is a good writer and they've crafted a very involved story with characters that people have really come to love, but they're not Shakespeare, or Hemingway, or even Stephen King. This is, at the end of the day, a porn game based on the college/school comedy genre of movies, and whilst I do expect some twists and turns, and I fully accept that the Burg theory may not turn out to be true, it is not outside the realms of possibility and would work perfectly well without bringing down the quality of this game and its storytelling in any way.