Sending SMSs from Address Book was a phenomenal feature. A shame that they yanked it years ago. Good to see its return.
It sounds like you underestimate how hard it is to have "UI polish" implemented just right so that it feels seamless and natural instead of a hack (because honestly we do love to hack but ultimately prefer our prototypes to be implemented first-party, e.g I've been using JACK to stream audio in sync on various devices for years but AirPlay is so much more simple and natural)
I'm aware that implementing this well is a difficult problem and I have utmost respect for those who figure out how to make it feel seamless.