I think that the practice itself is necessary - there are simply cases where the rest of the justice system gets it wrong, or the executive wants to make a change (like when Biden pardoned anyone convicted solely of small federal marijuana crimes). It has ALWAYS been vulnerable to abuse, tho, and it has only been societal/political norms that has kept that abuse as low as it has been. From what I can see, there have only been 3 (now 4) president who have pardoned their relatives - Trump pardoned his son-in-law's father, Clinton pardoned his brother for old crimes, and Lincoln pardoned his sister-in-law, who was married to a Confederate General, as part of the Amnesty and Reconstruction.
And PLENTY of presidents have pardoned their friends on their way out. Maybe Carter didn't, but he's about the only one I can think of. Oh, and Nixon, of course.
But I think it's reasonable for Biden to believe there is a distinct possibility Trump and the MAGA crowd would continue to attack Hunter for no damn good reason. Also, frankly, there's not a lot of point in trying to do the right thing with Trump and his cronies coming in to destroy everything. I guess I'd say he was wrong to do it, but did it for the right reasons.
Carter is probably the only president in 70 years that isn't a criminal.