This is useful sure, at least now you can save a Bitcoin address for a contact and not have to reuse the address which is even worse for privacy, but let's be honest, it's not private at all. The sender can very easily find out the real address the btc was sent to simply by monitoring the timeframe in question for the exact amount he knows he sent. Anyone else at a later date can do the same. I would argue this is more of a convenience feature than anything to do with privacy.