Although I am not the OP and you analysis is generally true, here is a scenario where a server side CD burner in a locked lights out datacenter makes sense:
A modern CD/DVD burner is actually a complete replacement for the historic optical WORM drives that were popular for some server tasks in the 1980s. One use for such a drive is to burn an indelible log of accounting transactions, stock trades, syslog events or other such data that must be protected from destruction by people with full (remote or near-local) control over the host and virtual machines.
In this scenario the drive would be assigned to a single virtual machine, which runs the logging and burning software. About once per day (perhaps less, perhaps more depending on data amount) a trusted person with no knowledge of the root passwords etc. would be allowed to walk into the room and swap discs, promptly depositing the retrieved disc in a one-way strongbox (like the once used for cash in robbery-proof convenience stores). If there is later suspicion of foul play (remote root compromise, insider fraud, accounting fraud, lawsuits over authorized trades etc.), a team of auditors with eyewitnesses, video cameras for evidence etc. would retrieve the relevant discs and read the audit trail.
Beware that most products currently marketed under the "WORM" term are read/write media with a "promise" that the drive firmware will refuse overwrite requests, unless the firmware is compromised (usually trivial once the system is compromised, if the attacker has studied the firmware). In contrast CD-R and DVD-R/DVD+R are physically WORM media, the only thing that can be done to written data is to irreversibly destroy the media.
