I actually read this in the new ToS. First one I've actually looked through in years! Big deal, I can't think of any situation where I'd sue them anyway. I don't have the energy and willpower to go through with a lawsuit!
Lawsuits generally aren't something you plan to do. They are usually done in response to something unexpected. I don't think many people joined the PSN with expectations of joining a class action lawsuit when Sony leaked out personal information on millions of users. Also the threat of a potential class action lawsuit hopefully prevents some decisions that would have lead to one.
I've never personally participated in a class action lawsuit, but I don't think there's too much work involved if you are just joining one someone else started.
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Pokemon VGC2011 US Nationals - 54th place
Pokemon VGC2012 NW Regional - 16th place