I think there are times when freedom needs to be enforced through law, as the GPL does, because the consequences of losing the freedom is too great (injury or death included). The GPL was and still is important, it helped popularize the free software movement. Twenty years ago the GPL might have been required, maybe the software landscape was such that non-GPL free software would not succeed. I think now, in 2012, it is not required for most projects. I will concede there are projects where it is still important.
If you look at some of the most successful and thriving open source projects you'll see they succeed without laws enforcing their freedom. Things like Apache httpd, nginx, Hadoop, Chromium, and X.org. People and companies contribute to them even though they are not forced to.
If think there comes a time when societies and ecosystems no longer need such strong enforcement of freedoms, and freedom is actually increased by not forcing freedom.
Here's another analogy. If I build a restaurant and want it to be non-smoking, I'm not restricting your freedom. You are free not to come to my restaurant.
Also, this holds true with copyright: If you don't want to pay for it, don't pirate it.
I like your drugs and alchohol analogy.
With free software, you as an individual have the freedom to do whatever you want with it in your home. That is your choice. You do not have the freedom to prevent others from modifying or reproducing it. Because when you do those things you take away the freedom of choice of others, you impose your will, you take away their right to modify and reproduce the software.
The point you seem to be missing is that licensing software is not something you do to the software. It's something you do to other people.