This is an excellent example of the "seen" vs. the "unseen". Sure, the FDA has stopped harmful and/or ineffective drugs from coming to market. But the FDA has also stopped plenty of effective drugs from coming to market, both directly (e.g. no more Vioxx because it might slightly elevate your risk of heart attack) and indirectly (the billions of dollars it costs, directly due to FDA requirements, to bring a drug to market).
Is the assurance that FDA-approved drugs are safe[1] worth the inhibited advancement of medicine? I don’t know, but I doubt it. I think a much wiser approach would be to have potential drugs freely available, and subject to testing by third or quasi-third parties (ala Underwriters Laboratories). Hell, you could even leave the FDA in place if you want to, only limit its ability to restrict drugs to market. For example, you could reverse their decision-making criteria: FDA will only pull drugs from market if it can be shown that the drugs are more harmful than beneficial for their intended use. This would leave the choice to use a certain medication to individuals and their doctors, with guidance from FDA/labs who conduct the same sort of testing the FDA does now.
[1] Note that the FDA’s stamp isn’t really an “assurance” anyway. Vioxx (and loads of other “harmful” drugs) still made it to market.