I suspect there's some small measure of protection still - if there's a brand new exploit available (say, the current WordPress W3 Total Cache and WP Super Cache problems), I'd rather not have my sites rise to the top of the list of addresses for the botnets to start probing - because I'd left the version information publicly available (or made those sites trivially findable via a googledork).
It won't protect me, but it might buy be a little extra time to respond...
It won't protect me, but it might buy be a little extra time to respond...