In my experience, the copyleft provisions of the AGPL are misunderstood by just about everyone to be much more viral than they really are. E.g. "if there is some AGPL software on a workstation or server, we might have to release all source code in the company!"
I wouldn't be surprised if MongoDB has been spreading FUD for years to cause this.
I agree with this, AGPL is aimed to be comprehensible in its permissiveness, but most folks don't know AGPL from GPL and, even with AGPL, there are ways to have infectious copy-left licensing if the raw binaries are directly linked into an application.
Thus a provision reverting to a BSD-style license in case of proprietary licensing would, I believe, do nothing to encourage them to use it in the first place.