In short, I dunno!
Get in touch with Leica themselves. Perhaps it has something to do with brass is more easily machined than titanium and not many of their cameras get melted down.

Brass has served Ernst Leitz and now Leica for a century, so why change a proven formula. All the essential working parts will be somewhat better and robust materials with the idea in mind that they can be repaired time and time again. Were the screw thread mounts of the early interchangeable lens Leicas also made of brass. I never heard of a screw thread camera failing because it was brass! The later ones (M Series) would have the mount made from stainless steel which is more than durable enough for a camera and ideal for a bayonet.
Also Titanium will be far more expensive and more difficult to make complex moldings and pressings and so bump the price up even further. Brass isn't an inferior metal, it is just different and suits the task in hand. besides when the 1st Leicas were made had they even discovered the properties of Titanium?
(Apart from anything else I don't like point and shoot cameras

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