As a gentoo user I would say that the ABI break may still worth it if it can enable a lot of application continuing to work with just a recompile, right?
The controversial around this plan origins from people's inability to understand why such a fundamental library like gtk+ needs to have api break in such a high frequency, which would have a huge impact on the experience of app devs and users? The world has its intrinsic complications, but we all hope to avoid the casual one.