No, actually it did. People expect tethering to be free just because it happened to be free when the phone released. That clearly was not going to be forever and is NOT a part of a "pure Google experience". Google isn't stupid, they know carriers aren't going to give you free tethering considering what people do with tethering now a days.
You should read the page that was linked. The asterisk only applies to the tethering section which means that tethering may or may not cause extra fees on your account. If this asterisk wasn't there and someone tried to tether and was charged, Then they could complain that Google never said that was happening and try to sue. It's called "Google is covering their ass".
Sprint is charging for tethering, not a big deal. Pay the $30 or don't.
No one is saying you can't be disappointed, but that doesn't change the facts. Tethering is a part of the Google experience and cannot be removed on the Nexus S,
however, the act of using tethering will cost you.
Sounds like you should've done some research before you bought the phone so you knew what you'd be getting into.
http://www.androidcentral.com/sprint-hotspot-will-still-cost-extra-nexus-s-4g-forums
Sprint never said that you'd get free tethering and nor did Google. It was always meant to be something you will pay for with Sprint.