If rollbacks are not safe then you have a change management problem.
If you have a good CM system, you should have a timeline of changes that you can correlate against incidents. Most incidents are caused by changes, so you can narrow down most incidents to a handful of changes.
Then the question is, if you have a handful of changes that you could roll back, and rollbacks are risk free, then does it make sense to delay rolling back any particular change until the root cause is understood?
If you have a good CM system, you should have a timeline of changes that you can correlate against incidents. Most incidents are caused by changes, so you can narrow down most incidents to a handful of changes.
Then the question is, if you have a handful of changes that you could roll back, and rollbacks are risk free, then does it make sense to delay rolling back any particular change until the root cause is understood?