It's legal where I live (UK, still within the EU, thank God) and I do use this stuff. Partly because I want RealMedia playback, but mostly because nasty corporations who use patents in bizarre, unnatural ways would rather I didn't.

Additionally, crippled US version of Ubuntu? Ridiculous stuff and for several reasons.

1) There's absolutely no way the knowledgeable US Ubuntu userbase would stand for it. They'd switch within days and Canonical would lose the entire US market.
2) It's hardly in keeping with the spirit of the Free Software Definition.
3) rms would hate Canonical forever if they did this, and suggest either a fork or just switching distros, and while everyone calls rms a fruitcake, they still listen to him in the end.
4) People would hate Canonical for it. Even moreso than people hated Novell for the awful patent covenant. In the tightly-knit Linux community, the support of the community matters more than life itself.
5) If the nasty corporations were going to sue, they'd have done it already. Microsoft for one has shown conclusively that they're willing to sacrifice their dignity in exchange for legal prowess.
6) If the nasty corporations were going to sue, they'd sue the Penguin Liberation Front for providing the packages rather than going after every distro that uses them. Cutting off the head is easier than going for one of a million arms.
7) If the nasty corporations were going to sue, they'd make a lot of noise and FUDish sounding press releases before actually resorting to taking on the most loved Linux distro in the history of the universe.