Seriously - not everybody wants auto shut off. That is why you can choose the setting in most cameras to off if you want to. I think Leica was right when they excluded it from a camera like this. Just turn it off when you stow it away - it is that easy!
Someone stated that with a camera that has no screen and no built-in AF, the response time by half-depressing the shutter release should be instant. That means it is just the screen that takes time to turn on and you're forgetting all the other electronics inside.
And the light meter in all those old cameras were on the moment you power them, completely different from the electronics of modern cameras.
But it seems opinions are mixed, giving Leica a big problem - some people want auto shut off, others don't. They need to find a way to switch it on or off by the user.