SED - Self Encrypting Drive
I came across the same site as Rod, and their comment, but can't say that I've actually noticed any such option with the few Yosemite installs or Migrations I done providing such an option, and ArsTech gives a bit of a varying view:
OS X 10.10 Yosemite: The Ars Technica Review | Ars Technica
But it seems a bit scary if the average or new user just accepts any FileVault enabling just because Apple may suggest it without realizing what it actually involves. And especially when so many users, as mentioned here, can't even recall their username password.