Its a very naive to group all drugs together. There's a whole lot of difference between pot and heroin for example. Recent studies show that alcohol and nicotine are more harmful than pot, e and acid.
Many great cultures in this world believe that drugs are an important part of spiritual development. Don't blame the drugs. Blame the loss of ritual.
As a songwriter, I have written my best songs sober but I usually formulate the ideas better while intoxicated. Most of the best songs I've written have come from times when I was into drugs and alcohol way over my head or when I was trying to sober up. The important lesson for any drug user is that soberity is also important. Sober moments are when you can put to use what you have learned from drugs. I believe that exploration of drugs can be a period of amazing growth in anyone's life but they have to be smart about it--make sure that some sort of spiritual exploration is involved in your drug use and make sure you pure stuff.
I once attended a Navajo peyote ritual and it is still one of the defining moments of my life. The ritual is important. Most drugs are plants and they were put here for us as tools. That said, you gotta use the right tool---you don't hammer nails with screwdrivers.
As for sex, its always better with someone you care about but a one night stand here and there can be a lot of fun.