The same reason some people in this forum went to the Jewels this past summer, ended up complaining about Emeralds performed by POB, I assume?
All right, my above remark was sarcastic. But a die hard Russian ballet fan has every right to attend and may also enjoy non-Russian school ballet (and Russian schooling is much more than Vaganova training). I mentioned my preference only because the NYCB production, no matter how the company has claimed, is mostly based on Petipa's choreography, a representative of Russian school ballet. Ballerinas from other schoolings with a different style, however, may still be a bona fide Petipa Swan Queen interpreter, as long as they understand Petipa's intention and display certain specific qualities under his intention. For example, Margot Fonteyn and Elisabeth Platel are two Swan Queens I utterly appreciate. Of course, Swan Lake is repeatedly subject to all kinds of deconstruction, some of which I find insanely interesting and enjoyable. But it's another topic since this is not the case with the current NYCB production. It is merely a cash cow taking advantage of Patipa. The choreography was altered for practical reasons instead of aesthetic ones.
In addition, people go to events they don't really enjoy all the time. You may go to a movie because your spouse like it. You may go to a football game just to socialize with your colleagues. You may go to a random event when you feel bored. You may even go to a live performance because you have heard it is a train wrack and you are curious how bad it could get. Anyway, I may spend my honest money on any performance and I am entitled to dislike it. It is indeed unreasonable to assume people only go to performances they are likely to enjoy.
I don't owe anyone a reason to go to a performance of Swan Lake at NYCB, but I'm writing it here now. I would like to give Ms Peck and Ms Fairchild some benefit of doubt before I saw their performances. They could have been another Margot Fonteyn or Elisabeth Platel, or to a lesser extent, Tamara Rojo or Gillian Murphy.