They're looking at this all backward.
If they made fun, light, quick, great handling cars with manual transmissions they'd find the market.
But when you make only over-powered, heavy, luxury cars for rich folks, you reap what you sow. Just sticking a manual in such cars is not really what people want. Nor is it even appropriate.
Go back to the 1M if you want to find your market. Or even my 128i M-sport stick, which could be the last 4-wheeled BMW I ever buy!