That's partly why many people see a Phd as a luxury or as something not entirely useful or necessary. Many people NEED to make money RIGHT NOW.
The only other possibility for getting money for doing your PhD is trying to get a scholarship. If you aren't near to either a big religion or a political party (I'm not to any of both), there's virtually only "Studienstiftung des deutschen Volkes" (German National Academic Foundation) which has really strict (and many people say: really strange) conditions of admission.
Of course, there is good competition, so it might be harder to get such a position.
YMMV but if you're thinking you're being used for cheap slave labour, you're in the wrong university.
I like to refer to Feynman's writings on this matter: http://www.pitt.edu/~druzdzel/feynman.html
To me, this process started only after I left the safe and controlled environment that is college. Graduation was like someone lifting the veil: I suddenly started seeing with great clarity and had true freedom in terms of what I wanted to pursue learning (as opposed to only the illusion of freedom given in an academic setting).
I'd say the only advantage academia has is being surrounded by other smart people. Especially now that I live in Southern California, where big biceps are seen as more important than a capable mind, I miss the college environment a lot. But that's the only reason.
I think you are missing one important advantage: in (good) universities, the environment is set up in such a manner that you can think and experiment all day without being bothered.
This is something I noticed profoundly when I started to work for a company after my PhD: in university there are relatively few distractions - the environment is set up so that you can think and experiment. A company is far more hectic, always has pressing deadlines, etc.
Both have their advantages: in a company there is more frequent gratification and you can leave your work at the door. In academia on the other hand, there is much more time to puzzle until things are really 'right'.
Sure, I'm not making much money (people always bring this up). But who cares? HN is full of posts about how to live minimally, it's kind of a classic hacker challenge, right? I may need money someday, but right now I don't, so I might as well take advantage of the situation.