FWIW there are 3 options:
1) Default on.
2) Default off, not specified in standard configs.
3) Default off, but set to on in standard configs.
The distinction between 1 and 3 is people bringing an existing config do not see a behavior change.
No matter which we do we should aim to get this in very early in a release dev cycle so we have time to notice any odd impacts.
Do you have any thoughts on how we can look for odd impacts? IIRC the odd impact would be stuff we expect to appear in the server.log no longer appearing there.