I'm sorry Tom but in my opinion optical drives are still relevant to a lot of people. Just because Apple are at the bleeding edge of removing technology from devices is not an arbiter of what is relevant. Not that Apple are even consistent about that, just look at the 3.5mm TRS/TRRS headphone jacks situation. Remove them from the latest phone, in preference for a new proprietary connector, then launch the latest top end laptop with the old, not new connector! There are still many places that sell pre-recorded video titles on DVD, and for those of us who are not blessed with the worlds best quality internet connections they are a useful fall back position for a little light entertainment. Having an optical drive so that I still have access to the collection of movies that I already own on DVD, after initially buying many of those titles on VHS and having to then replace them once already is a must on any desktop system I might own. Oh and yes I do have less than ideal internet speeds, with some days it being somewhere between frustrating and impossible to do anything productive that requires a connection. At the moment I would not buy a system without at the minimum a DVD RW drive.
When it comes to the question posed by the OP I would tend to agree that in general a DVD is now very unlikely to be popular with most clients. Mostly this is because many of the younger ones these days are actually becoming less likely to even own a computer. At best they may be using a tablet, otherwise they are using a phone, or maybe if they really want a larger screen, a smart TV. They can probably play a DVD into the TV, but the phone/tablet is likely to be the first choice viewing device now. So I would also be suggesting a private online gallery for viewing the images, and ensure it is optimised for viewing on a phone and then a tablet, before you consider any other type of device at all.
Alan