That depends on what the alternative is. If you allow imports of drugs that are already approved by the FDA, then the objections are mostly about economic ince

That depends on what the alternative is. If you allow imports of drugs that are already approved by the FDA, then the objections are mostly about economic incentives (i.e. high prices reward the companies that made the drug, etc..) If you allow imports on drugs that are approved in other countries but not by the FDA (iirc this was advocated by Ted Cruz in his debate against Bernie Sanders on health care a few months back), then the objection is that it basically neutralizes the ability of the FDA to block dangerous drugs and makes it easier to push drugs to market that aren't ready by promoting the drug in whichever country has the loosest standards or is most corrupt.