I’d like to think it just has to do with the buckle looking weird in the larger size—it already feels kind of huge as a 41mm and I wear large only a few off the last hole—but it’s probably just the gender politics of fashion. I guess there’s also the fact that the Granada/NASA leather is seamless and pretty thin; that slightly off-kilter ratio would be intensified with the 45mm.
Apple made a prototype of the Deployant/butterfly style clasp and put in on the classic buckle leather, fwiw. I’m guessing that would have been the move for a Modern Buckle counterpart with perhaps a more masculine targeting.
I’m surprised it still sells well enough to have survived into the link era when the loop finally got killed off. I love Garnet, as well. Perhaps I can envision someone who wants some elegance to set them apart from the default sport band masses but not at the Hermes price level shopping all the options and getting MoBu as their primary, with scant use of a sport-style if they exercise.