First of all, the name date rape drug attracts a lot of attention in the media. The main drug used by a rapist is still alcohol, and the second most used drugs are barbiturates: Valium and others. GHB is not used very frequently for that purpose, but it is used for other purposes, as are several drugs. In fact, in order for there to be a rape, you need a rapist. That is the main condition. Drugs do not create rape.
Second, I found it difficult to criticize minimum sentences. It is as if we are being told that we do not see a problem. We see the problem, but we do not propose the same solutions.
Contrary to what people may think, legalizing drugs reduces their availability. Put me on a black market anywhere on the planet and in three hours I will get you what you want. In a black market, anybody can sell anything.