My guess is that it helps a lot that we have flexible cushioned fingertips that are highly sensitive to pressure. That's a hardware feature that robots mostly lack.
Imagine if the tip of your finger could just bend back. It would be way harder to know what you’re touching!
I don’t think so. I have hitchhikers thumb, so my thumbs do bend backwards. They don’t feel disadvantaged in terms of touching compared to my other fingers.