Because whatever abuse proof pill they come up with will be defeated. At the end of the day the drug still has to be available to your body, and that limits how much you can do to make it "abuse proof." The closest thing I've seen are shifts toward prodrugs that have to be broken down in the digestive tract to be active, but even then you can just take more. Even if enzyme availability rate limits the maximum effective dose you can take, how is this going to be beneficial to patients? The obvious example is someone in extreme pain, but the new abuse-proof pro-drug enzyme rate limited Oxycodone replacement means your body can only metabolize the equivalent of 20mg of Oxycodone a day. So if you're in severe pain and you have a tolerance? You're fucked, and they're going to have to keep stronger medications around to take care of you anyway.
People who want to get high are going to get high anyway. All "abuse proof" medicine does is make them resort to crazy, dangerous lengths to try to do it, like trying to shoot up time release pills. Prohibition advocates need to realize that a lot of the measures they take to try to protect us from ourselves are actually hurting us more than if we could just go up to the clerk, show some ID, and buy taxed Oxycodone. How many of your connects out there care if you're over 18? How many drug dealers do you know who pay income tax?
Tell The Man how to make his abuse proof pain med, and then watch OD for the tek on how to bypass it within three days of it hitting the market. How would you like to be the drug company exec who spent a billion dollars researching a new drug, getting it through human trials, getting FDA approval, etc. etc., to finally get it to market, and then a week later some junkie with with a 10 cent razor blade and a 2 dollar bottle of lemon juice or something defeats your wonder drug.
Abuse proof medications do not work for a lot of the same reasons that DRM or anti-piracy measures do not work.
So take the survey and help Bluelight, because the overall historical cycle of how this works is that The Man always gets fucked. These are the same people who thought heroin was a safe replacement for morphine, and that DXM was an abuse-proof replacement for codeine.