I have a couple of points regarding the "inability-to-sue" concerns:
1) Linux has precisely the same issue, and is clearly commercially a lot more relevant than Wikipedia. In all the years, nobody has ever had to file a suit. People occasionly violate the GPL inadvertently and back down once it is explained to them.
2) Bomis has standing to sue: Larry is an employee of Bomis, and as such all his contributions are automatically copyrighted by Bomis. He has edited a significant proportion of the articles on the site.
3) Imagine you're big bad Microsoft, about to willfully violate the GFDL. Which scenario is scarier: being sued by Bomis.com, or the prospect of being sued by hundreds of volunteers from around the country, even around the world, with lots of sympathetic press coverage?
4) Money for such suits wouldn't be an issue. FSF, EFF etc. would all be happy to provide pro bono lawyers. By contrast, Bomis wouldn't get nearly as much support. "Just two companies with some copyright disagreement -- who cares?"
Axel