I admit I wasn't sure of the first name, but It would have been my second guess. I think most people would guess either "E" or "C" and get it, so I don't think it matters.
Eh, I see your point, but people generally lump the Bronte sisters together mentally, so if you know it's by a Bronte, then you just need to shuffle through the three names (or, if you don't know Anne, the two names) and you'll get it. I think allowing the last name only is basically just saving time.