It's a little late now, but I might suggest in the future of that rather than radically change an API interface, even between major versions, you launch it as

It's a little late now, but I might suggest in the future of that rather than radically change an API interface, even between major versions, you launch it as an entirely new package. While I really appreciate the work that you guys have put into this library, I think what everyone is really frustrated about is the heavy change between versions. This creates a lot of logistical headaches and perception problems that have upstream consequences, some technical and some political.