I recently adopted Thunderbird as my email client (was using Gmail's web UI) and have really appreciated the power of it, enough that I donated to the project. NOT being like current designs has been part of the appeal. This development sounds high-risk, low-reward from my perspective. Could well end up nerfing the tool I just adopted. But c'est la vie, I guess. Probably the mistake was leaving Thunderbird without real governance back in 2012, so now as it's pulled from anarchy it's going to be painful watching "the law" of centralized development come down.

I would prefer if it were a more democratic process.