I don't know the extent to which this is a problem (i.e., I don't want to make this into a "weak man"), but there are some legitimate reasons to be concerned with the replacement and/or minimization of traditional holidays. At least one important motive for the replacement was to create the foundation for violent revolution: "the creation of its own series of holidays all underscored Karenga's premise that 'you must have a cultural revolution before the violent revolution. The cultural revolution gives identity, purpose, and direction.'" [0]

It's easy for people to laugh at such concerns when they don't see them as plausible, but when you also have people like Dick Costolo promising shootings and a violent revolution, it's hard to know who can be trusted. When the left spends a year "mostly peacefully" killing dozens of people and burning our cities, it becomes a lot easier to believe that they might want a full revolution. Again, not to say that these concerns are necessarily justified, but that it's very difficult to know whether they are or not. If one prefers to err on the side of caution and criticize Starbucks here, I think that's a legitimate position.

(Kind of hoping that someone can give me a good way to debunk these concerns, so I'm just going to ignore any troll responses).

[0] https://books.google.com/books?id=Vhgk72OGBRYC&pg=PA65#v=one...