They are open source developers, giving away free software as a gift. There is no duty here.
We can speak, respectfully, of how important backwards compatibility is to us, and ask nicely for them to give more of their time to support it when their free sodftware isn't backwards compatible. Perhaps we can even offer to help implement it.
But they have no duty to do so or to "care" for their users. (They have already demonstrated they care for their users, btw, by giving them free software.)
EDIT: I missed an important part of the story, which is that they mutated existing files in a non-backwards compatible manner. That should have been avoided, I understand where the (secondary) author is coming from now.
We can speak, respectfully, of how important backwards compatibility is to us, and ask nicely for them to give more of their time to support it when their free sodftware isn't backwards compatible. Perhaps we can even offer to help implement it.
But they have no duty to do so or to "care" for their users. (They have already demonstrated they care for their users, btw, by giving them free software.)
EDIT: I missed an important part of the story, which is that they mutated existing files in a non-backwards compatible manner. That should have been avoided, I understand where the (secondary) author is coming from now.