thanks for this post, i hope people take the time to read this. i knew this about the brush sets, but i know everyone does not, and it still gets asked a LOT on the various MAC boards. your post did a good job of actually listing the reasons why the sets are not as good.
clearly, for the prices, you can't expect the brushes to be as high quality. they are mass produced, and all-around cheaper than the full size ones. still, they aren't totally useless, and are probably better than some of the other brushes on the market, especially the ones that come in free-gifts from other cosmetic companies, or cheap sets found on ebay. they are great for travel, which is why i have all 3 sets from this year, they go with me for a night out, or on a trip, because i wouldn't be devastated if i lost them. i refuse to let my full-size brush roll leave the house, because i have hundreds of dollars worth of brushes invested in that roll, and i would hate to see anything happen to them.
my recommendation is to build a full-size brush set slowly. start with the basics. people complain about the prices of the individual brushes, but they last a long time, with proper care, and really are of top notch quality. if you can't afford them at one time, buy the set over a long period of time, and slowly build a collection of full-size brushes, don't blow $50+ on a brush set of so-so quality that won't last as long. it's better to be patient, and get something you know is worth it, and will work in the long-run.