First, no artist was *ever* forced to go through the big labels. Until recently, they provide better access to the market place than anything else (and I think we're all better off because of it), but that is a *choice*. Big difference. Having your work pirated is *not* your choice.
Second, in the last 100 years, we've seen a huge increase in the variety of music, books and art that is generally available to the public that puts any other era in human history to shame. If the *IAA have successfully stifled creativity, it's pretty hard to tell. (Remember, the era of real RIAA power is 1960-1995, often considered the "golden age").
And lastly, the idea that pirating artist's music is justified because you don't like the RIAA makes about as much sense as piloting jet planes into buildings because you don't like American foreign policy. There's a massive logical disconnect between the action and the target of hatred.
Honestly, I find hatred of the RIAA pretty thin moral justification for stealing from artists. Honestly, I don't care if you're stealing. Maybe you can't afford the media (but can afford several hundred dollars for a computer to post here). But let's not pretend it isn't stealing, even if it's pretty low level.