Remember that Keiko was never close with her family, and doesn't seem to have any good memories at all of her parents.
This true, but in my experience even those families which kids don't have fond memories of still do the whole holiday thing. But maybe that is the case, I mean I don't think we've seen her dad even mentioned once. Too busy doing that salaryman thing I guess.
From my admittedly brief reading on the subject, it appears New Year's soba is a common thing for families. Perhaps someone with a bit more knowledge of Japanese culture could weigh in?
It's quite possible, but Isn't really relevant to all families.
Thanksgiving all about the turkey for millions upon millions of Canadians/Americans. But in my family this is not the case.
Reason is pretty simple, why would you eat inferior dry meat that you need a bucket full of gravy to even eat the thing?