The R Leicas have mostly been far inferior to Canon and Nikon pro models (such as F1). Having them made by Minolta didn't help. Obviously, one pays far less for a Minolta than a real Leica.
Pros ( in ancient times, when they still shot film) mostly shot Nikon or Canon SLRs. A few oddballs shot "Leica" SLRs.
The market knows.
Interesting comment, and I think you're correct. Wetzlar-heads will probably crucify me, but....
Leitz competed for the working professional market in both the L39 and M days, and provided a full range of gear aimed at the needs of professionals, photojournalists in particular, but also including accessories for everything from Macrophotography to Astronomical.
They were relatively latecomers to the SLR game, in my opinion primarily because they didn't recognize that SLRs offered any advantages for professional use. Oddly, they viewed their own M rangefinders as their professional line, and from the very first, offered a more limited range of SLR gear. They seemed to recognize that they were late to the party, and, again, IMHO, they never expanded their R lines to include stuff that pros were taking for granted in their Canon and Nikon systems. When I first shot a Leicaflex (the non TTL metered model) while working in a camera shop, two things struck me: 1) This is really made like a Leica, it's gorgeous! and 2) Don't these guys know that the through the lens exposure meter is a thing now? The widest lens was a 35mm, the longest a 135mm, and neither was particularly fast. The completely ignored the exact qualities that made SLRs the new professional paradigm - range of focal length, accurate metering, and fast glass.
This was at a time when their M series lenses went from 21 mm to 500 mm, and their ultra high speed 50s were far superior to anything from the Pacific rim. The original Leicaflex and its descendants were relegated to expensive toys for dilettantes, and were never a serious alternative for professionals. The rangefinders remained a favorite for a limited range of professional journalists and street photographers but many pros needed a pro SLR. The R lenses were, again, in my opinion, wonderfully sharp and felt great in use, but they just weren't designed to meet the needs of professionals.
Sadly, Leitz just didn't believe in the SLR concept, and lost their chance to be in the forefront of developing that market. Prestige means something to the amateur hobbyist with a fat wallet, but not to the pros. Sentimental attachments aside, by the 70s, the SLR had taken over the pro market, and Leitz didn't have anything to offer. Today, they're great bargains, I think. I'm not a pro, and I don't need the latest and greatest, so looking at old Leicaflexes and R lenses on auction sites is making me think seriously about jumping in.
Andy