While I agree in principle that "holding one's games hostage" was a bad thing, you should listen to Gabe Newell's reasoning behind the TOS change here (fast forward to about 8:15). If you read the TOS, it doesn't talk about not being able to sue them, it's about not being able to start a class action suit against them. As Gabe Newell (briefly) explains in the video, the class action suits they face start out very one-sided in favor of the suing attorney. It costs them a ton of money just to go through the motions for the court, no matter if they're completely in the right or not. That's not exactly fair, regardless of how much money anyone thinks Valve has. As it was put in the video, "it's a shakedown."
Having worked as a class action attorney, I do agree with you to a certain extent. Many class actions are simply shakedowns by plaintiff attorneys. But they can also be one of the only ways to hold a company liable for their wrongdoing. Are you, or anyone for that matter, going to sue Valve/Steam for $50? I know I wouldn't go through the hassle of a lawsuit for so little money, even if I had a bulletproof case. And this works to the company's advantage because if they can take $50 from a million people through wrongful means, but none of those people will sue individually, then the company essentially just stole $50 million with no risk.
Granted, the attorneys on both sides see most of the money. But if you look at class actions as taking unjust gains away from companies, rather than reimbursing consumers, class action are, other than government action, the only way to really hold these companies accountable for their actions.