The point is, they release brush sets for portability, to introduce new customers to their brushes, and so on. How would it be practical at all for the average user to have different brush sets come out all the time? Usually people buy a brush set once, and then maybe again when their old ones need replacing. What would be the benefit of not making the basic, standard brushes always available in the sets?
It seems silly to me to expect them to release a variety of brush sets. Why would they want to make it easier for you to have all or most of their brushes at a much cheaper cost? It seems like people are expecting them to cater to collectors or to professionals. They do already with the PPID and pro stores.
When I said fair, I meant how would it be fair to the average user for MAC to release different brush sets, when what most ladies need are the basic ones, which are only available a couple times a year as is, just to cater to people who buy multiple sets or collect them, which you have to realize is a very small portion of their customer base. Not to mention that it would not be smart business-wise either.