Having Hangouts as a full featured SMS/Voice/MMS replacement, which also let you do all of those things from your computer was an awesome experience. GV features like Spam filter wasn't supported with Fi, and just accessing your GV account with a Fi subscription on your google account was difficult.
Then they split SMS/Hangouts (although Fi users were somewhat grandfathered in), which broke basically every text convo I had going on, and made it more difficult to text Hangout friends compared with SMS only friends. Then they rolled back the gVoice/Fi plans, and made it clear that Hangouts was going away, and gVoice wasn't going to be an option. Then the Nexus phones started to get worse instead of better. The 6P was mediocre at best, and "Stock" Android was starting to make compromises, while somehow getting worse. The Pixels have continued this trend of decline, Hangouts can't really even send Gifs anymore (size limit of like, 3mb or something) Fi has made almost no progress, and when Hangouts goes away I'll be retiring the last of my Android devices.
Kind of a long rant, but my point is I don't trust google to do anything competent in this space, and even if they did, I wouldn't trust them not to fuck it up 6 months later.