IMO, Webpack (and React Router [0]) have been in this weird and honestly toxic place, where there was very little regard held for backwards compatibility and gradual deprecation by the core teams
at first, so businesses with larger apps became marooned on previous versions as soon as the first major version change... thereby not contributing their expertise and bug reports (they spent that time fighting against the lack of documentation), and thereby making it even more difficult for the core teams to get feedback on people's real-world migration woes.
It's fair to say that there were problems in the earlier APIs, but if that's the case, make changes gradually, even create an RFP process, tease/market your API change proposals to get feedback from people who might say "this is not something we can adopt easily, but you could add this param for backwards compatibility." It'll take longer to get to an API that feels "perfect," but it makes for a stronger culture.
[0] https://github.com/ReactTraining/react-router/blob/master/pa...