VoLTE is marketing.
I'm of the opinion that voice, text, and audio technologies should be standard issue freebies - they're basic services which are barely even monetized anymore, nobody even imposes limits on call minutes or msg counts anymore (within Canada) except on their ultra low-cost subscription offerings. The real commodity is Data, more capacity, more performance.
I doubt many people buy $$$$ premium flagship devices just so they can enjoy the finest in VoLTE voice calling. They buy it (at those prices) because of marketing. (And they don't buy the latest-and-greatest iPhone or Galaxy because they need tons of voice calling, lol, they buy those devices primarily to make heavy use of all the Data-based technologies.)
VoLTE is perceived as being valuable because of artificial scarcity. It's not an impressive enough thing in itself - to me - to justify the costs attached to it. My experience is that the people who want/need plenty of voice calling tend to be the same people who avoid texting and browsing and social media and gaming and apps, lol, VoLTE would be more useful in the real world if it was built into flip-phones.
It's worth noting that VoLTE's superior call quality only works when both/all calling parties are using it. And most smartphones de-emphasize actual voice/audio codecs (let alone their ever-cheaper speaker/mic hardware components), they tend to sound worse than devices from previous decades, because they lean more on software controls for everything.
