Honestly, a constitutional amendment should be passed to strip the President of his/her pardon powers. It is a bizarre, monarch-style power which has the potential to cause a lot more harm than good. Or at the very least, pardons should have to be approved by a commission of legal experts.
That sort of defeats the point of a pardon, no? The President has the power to pardon as part of the system of checks and balances — to allow for clemency and ensure that courts do not have sole authority over criminal sentencing. If legal experts can override that privilege, then there is nothing to check the power of the courts. The pardon power can allow the legitimately guilty to escape their sentences, but it can also allow the wrongfully convicted another opportunity for reprieve, and Blackstone's formulation tells us which one to prefer.
The Constitutional remedy for abuse of the pardon power, incidentally, is impeachment. (Ex parte Grossman, 1925).
A far better idea would be to also grant pardon powers to a panel of retired SCOTUS members, functioning outside of the lobbying system.