They gave their user base only one week's notice of the upcoming change[1], and according to the discussion in the original thread, had dark patterns in their UI that made it hard to opt out of the feature (it would only allow you opt out for 24 months)[2] or cancel your account.
I also got the email. I think the characterization is entirely accurate. (The bit about needing to opt out was badly phrased at best, and buried in the middle of a paragraph. I skimmed the email and thought it was a neat feature, and made a note to turn it on before my next job hunt.)