Isn't that already happening now? I know what we heard from the probation officers earlier. These sorts of judgment call are being made by probation officers all the time, about what information is relevant. I doubt very much that pre-sentence reports nowadays would contain irrelevant information about all kinds of things to be determined by the judge.
I suppose there are examples in which that's not true, but information relevant to the person's mental health condition, for example, is already in most pre-sentence reports, if it's relevant.
They can identify or pinpoint whether or not it is relevant to sentencing, can't they?