While I detest product placement in tv/movies, as it almost always "takes me out" of the show, I understand the reason. They no doubt find it necessary for revenue given the decreasing number of views commercials get. Between DVRs, bittorrent, Netflix streaming, etc., etc., fewer and fewer people are watching the commercials, and so they're trying to figure out how else to get money from sponsors.
There are definitely right and wrong ways to do it, though.