I got a call from BMW in response to my email and expressed my dissatisfaction w/EWS, and recommended that they make it an option. The guy on the phone said that this feature cannot be disabled.
Also talked to the dealer who said that my ring ant went bad and that this was the first time they've experienced this. One is on order from Germany, which will take at least 10days to get here.
The dealer also said that EWS cannot be disabled. Actually, I have a technical background, so I'm taking this to mean 'cannot be reasonably disabled'.
I was thinking about ordering a spare, but $160 is a little more than I thought it would cost.