Can this even be classified under UX? I don't see ways to revolutionize the business process that could stop users from scamming other users. Most scams fall under social engineering after all.
This can be frustrating when it happens to you, but I don't see any way to bypass it. We have QR codes for this purpose, but they're not always applicable. There's also no way to verify if the user is sending coins to the address he means to.
This one is especially challenging: How do you make the private key more accessible without compromising security?
I'm not writing this to slight you, it's just that as things stand, I don't see a way to improve anything as far as your points go. As for the complexity of the UX, it just seems complex because of the number of steps you have to take. Individually, the steps are rather trivial in nature. I see how it can appear daunting to some people though, since we live in times where everything is just a click away.