Leica like Rolex is all about name recognition. Rimowa is to luggage as leica is to cameras...As others have said, the price is an issue. And for pro use they have been sidelined for a long time. Before TV & Movies I worked in commercial photography for a while - ads, fashion, product photos, material for websites, etc. Never once saw or heard of a Leica being used on a pro job. Mostly Canon, some Nikon & Sony, and then Phase One on big-budget or really technically demanding jobs. Fuji medium format (well, semi-medium format) was just beginning to creep in when I left stills. While in school I was doing journalism work and shooting for local magazines, never saw Leica there either. Mostly Canon, some Nikon.
Leica doesn't really do zooms and shooting macro or tilt shift on a rangefinder is impossible. So that puts them out of the running in a pro's bag. Unit stills photographers on movies and TV usually use some form of mirrorless, so you could do that on Leica, but I have yet to see it.
Where I did see them A LOT was from fine arts students and camera club guys in the school darkroom. I stuck to Nikon since I could share one big set of lenses on my analog and digi bodies.
They're nice, well-built, and not for me.