@ArchaeoIain Perhaps it is is need of reform.
However, it would require a Constitutional Amendment and Amendments are both difficult to get and also risk revision of other elements of the document too.
Pardon powers significantly predate existence of the United States and at least twenty-four (24) other countries currently have a pardon power provisions.
Pardon powers exist for many reasons, including a chance to set miscarriages of justice right. Biden may use them that way in coming weeks.