The justification has, until recently, been that people need to be protected from themselves: they underestimate the amount of stability and buffer they need in times of economic exuberance and depression.

Also, it has, until recently, been very difficult to coordinate price changes across an entire economy in a quick efficient and automated fashion. Also, it's a lot of cognitive load to, while at the supermarket, calculate expenses for, say, a month in sats alone.

This is all to say "stable coins" have real utility. Bitcoin is what it is, I'm sure most on here who read this will have very complex explanations in their mind for what it is and how it works. One great thing that can be done on Bitcoin is to iterate and improve upon stablecoins in the way that your post suggests. It makes it much easier to coordinate a market for stablecoins. I'm personally really excited about Chaumian-mint, Taro and Spacechain based stablecoins.