Divers come in all kinds of aesthetics, from vintage elegance to brutal machismo, and everywhere in between. They only share a reasonably generous WR and a bezel, but otherwise come in every shape and form.
This range of aesthetics can suit all types of straps, because, surprisingly, things look good based on how they look. They do not look any better or worse because of the specification they were designed for.
Vintage Rolex (or Tudor) is one example, another might be all of the EPSA cased supercompressors, most of which look great on leather. I know my Pleamar (and my jumbo Chronostop) looked good on leather.
Do what you like, hard and fast rules are completely irrelevant.
D