Personally, I find the intense focus on API/ABI stability and legacy support in the software world to be a major blockage on the road to great software. I'm ecstatically happy every time a new version of Swift makes big breaking changes, because it means that people care a lot about making Swift excellent, and as somebody who has used many different languages and frameworks, I can tell you that care is acutely felt in the experience of writing with Swift and Apple frameworks. I'm paradoxically kind of disheartened to see it reach stability. I wish this went on for a couple more versions.