It seems that communities that mainly use programming languages for reasons of "getting stuff done" value backwards compatibility the most; they are the ones who would rather not have to spend the time "upgrading" things that used to work perfectly fine, and would rather use that time to do something more useful and related to their ultimate goals. Personally I think backwards compatibility is getting less attention than it deserves, and that software should evolve slowly and gradually and not suddenly make huge leaps, because all these breaking changes start to look like they're just creating unnecessary, wasteful work. Imagine if things like mains plugs changed every few months, with appliancemakers all adopting the newest backwards-incompatible version. In some ways software is easier to change than hardware, but at the same time we must remember that effort needs to be expended to perform these changes as well, effort that could be used in other ways, and often there is a lot of interconnectedness in the systems we are trying to change.