The FDA places the burden of testing on pharmaceutical companies. If they are not legally held accountable for the drugs they dispense, how can they be expected to perform valid, complete clinical trials?
I imagine that many pharmaceutical companies go through a condition similar to ''space fever'' before a drug is approved. After so much money and effort has been invested in research (especially for designer drugs like SSRIs,) spending years on guaranteeing safety will definitely seem less attractive than if the drug was discovered serendipitously.
Either drug companies need to be held accountable for what they market, or practitioners need to be held accountable for what the prescribe. The fact remains that sick people are always going to blindly take pills without researching their effects, and the government isn't going to do shit to help you.