I have questioned that for years now --- ever since we began seeing the ubiquitous ads for pills, with their laundry list of precautions and the 'ask your doctor' disclaimer. Unfortunately, it is not likely that the advertising will end without yet another darned law on the books.
Advertising generates revenue for the entire pyramid of leeches: the ad production companies, the model agencies and actors, the ad agencies which represent the drug companies, the television and radio stations that air the spots and the doctors who get patients requesting the newest fad pill. (Rarely do you see a genuinely life-saving pharmaceutical product; most are only life-enhancing and sometimes created to counteract a bad choice of lifestyle---it's easier to take a pill than to change your diet or get more sleep, etc.)
I find it ironic that many of the drugs pushed to the public are apparently not fully researched and then have to be pulled from the 'market' -- Vioxx, for example. Could it be that some drugs are being released before they are adequately tested so their marketing can start sooner?
Related issue: There used to be TV ads for Enron. Why? Other than to make their stock look good, I could see no reason. The company did not have a product that was sold to the public, so why on earth would they need to spend big bucks on advertising? (But then I've never understood why the United States Postal Service has to advertise either.)
I always laugh at ads by the electric company or natural gas company, too. Like I have a choice????
And I still haven't figured out why my cable tv company advertises on a cable channel. If I don't have cable, I won't see the ad; if I already have cable, I don't need the cable ad.
Such is business. One hand greases the other. [Whatever that means.]