If they could develop pain medication with the ability of opiaiates to block pain without the near orgasmic feeling it offers to many people that would be huge.. I doubt many of you have ever shot heroin or morphine, but during withdrawal which is probably the worse feeling the body can feel without actually dying if you 'reup' it's almost instantaneous when injected and you go from feeling absolutely horrible to feeling great within seconds and that feeling is almost impossible to put into words so the average person can understand.. if they could ever eliminate that aspect of pain killers it would change medicine as we know it.
I think everyone should have to go through that at least once in their lives, but if they did 99% of the population would be hopeless addicts.. Probably not such a good idea after all..
To almost every addict I've ever known that feeling is better than sex.. People wonder why anyone would want to shoot heroin, but that's probably the biggest reason I can think of..