Justice is not supposed to be impartial once a defendant has been convicted, shammydodger.
It is the job of the sentencing judge or magistrates to impose a suitable sentence which will fit the crime committed and, to a lesser degree, one which will be relevant to the offender. In order to do this it is necessary for them to know the impact that the particular events had upon the victim.
To say that judges are not up to the job if they do not realise the impact the crime had upon the victim is somewhat naive, bazwillrun.The same crime can have vastly different effects on victims and it is necessary for the sentencing tribunal to know about the individual circumstances.
As Barmaid said, Victim Impact Statements are read in court after conviction (though by the prosecutor, not the victim). They are not prepared as often as judges and magistrates would like, but where they are provided they play a vital role in the sentencing process.