I a previous post, I detailed how to get the Bitlocker wizard page to appear when deploying Windows 8 pro.
I recently confirmed another case where the wizard does not show up. I became aware of this thread on Technet because another user linked to my previously mentioned blog post.
I was able to confirm after a bit of testing, that when using the Windows 8 Enterprise evaluation media, MDT does not show the Bitlocker wizard page. At this point, I am not sure of the reason for this.