Q. Why is there no option to attach a physical DVD drive to a Generation 2 VM?
A. Generation 2 VMs can have a DVD drive added to the SCSI controller. However, these drives can only have an image attached via an ISO and not a physical DVD drive. There is no physical drive mapping option for a number of reasons, but principally because mapping to a physical drive breaks the ability to perform live migration. The best practice is to use ISO files.
Additionally most DVD drives use SATA and a Generation 2 VM has no IDE controller.