Now Google's decided to split SMS back out into a separate SMS app, so god only knows what's going to happen to Google Voice texting in that transition. I think the Voice team got merged into the hangouts team and shortly reassigned, and then everyone who was left on the hangouts team was moved a month or two after that.
Next time I replace my phone I'm just going to bite the bullet and port my phone number back out to a real carrier. It's a bummer, since this is the only Google product that I've ever paid them actual money for.
You can go into hangouts settings and turn off google voice handling.
So I guess I can go back. I'd miss the better voice calling integration (the one improvement that "hangouts dialer" brought) and I'm not sure how well maintained the GV app is these days, but I may give it a go.