I certainly don’t trust Facebook’s discretion in how users’ data is subsequently disclosed.

All the same, there may be a prosaic explanation for the policy change. Truly deleting data is hard — it requires careful system management and tracking of where a user’s data wind up. If data are used for testing, or digests of them are distributed to advertisers, then it may become extremely difficult for Facebook to actually remove the information of a user who closes an account from the system — even if they are acting in good faith. Facebook’s lawyers and engineers may simply have decided that it is easier to unfetter their hands ahead of time.

I am not suggesting that systems should be engineered this way, nor that Facebook is setting a good precedent (they’re not!). But they may not yet plan on “being evil” (to borrow a line from another organization that has progressively diversified its usage of users’ data).

Of course, once the fetters are off, temptation may be hard to resist.