Semantic major/minor version 0.15 means it's still in development. It's not supposed to be stable.
Going from 0.14 to 0.15 allows breaking changes.
Try making a similar change between version 5.0 and 6.0, with hundreds of thousands of existing users, programs, packages and frameworks that all have to be updated. (Yes, also the users who have to learn the new thing.)
Try making a similar change between version 5.0 and 6.0, with hundreds of thousands of existing users, programs, packages and frameworks that all have to be updated. (Yes, also the users who have to learn the new thing.)