At that point, Peter Chou's Facebook announcement, the EVO 3D was already finalized and was in mass production. They weren't going to halt production at that point to retroactively unlock the devices during a production run.
Once a device has been in the hands of the public for a week or so, an update is usually released for any new found bugs. That would be a logical point for them to do the unlock.
I was pleasantly surprised to see HTC respond the way they did after countless brush-offs from the Moto camp. Since they are outwardly taking a step to open their devices up for dev work, I will not hold them to the ridiculous expectation of launching the EVO 3D unlocked.