I can see the usability aspect, but using an insecure protocol like SMS for something like payment sounds like an absolutely awful idea. RCS might work as it's

I can see the usability aspect, but using an insecure protocol like SMS for something like payment sounds like an absolutely awful idea. RCS might work as it's a bit more secure (and more importantly: doesn't have a 2G/3G compatible version that criminals might trivially abuse); it even has an optional money sending API in its protocol.