Yes because it didn't exist at launch. They have since said numerous times (including today) that all PlayBook's will be updated to BlackBerry10.
OP it will be okay. They will produce BlackBerry10 for PlayBook but it won't be today or tomorrow. Just hang tight and enjoy it for what it does now. Who knows, you may finally get BlackBerry10 on PLAYBOOK and wish you had 2.1 back.