In regards, to "ABUSES" being at the bottom of the link. There was anchor text.
As for "recently" admitting abuses, the Church was addressing this issue as far back as the 8th century, and continued through the 16th and even unto now.
Among the good works which might be encouraged by being made the condition of an indulgence, almsgiving would naturally hold a conspicuous place, while men would be induced by the same means to contribute to some pious cause such as the building of churches, the endowment of hospitals, or the organization of a crusade.
It is well to observe that in these purposes there is nothing essentially evil. To give money to God or to the poor is a praiseworthy act, and, when it is done from right motives, it will surely not go unrewarded. Looked at in this light, it might well seem a suitable condition for gaining the spiritual benefit of an indulgence. Yet, however innocent in itself, this practice was fraught with grave danger, and soon became a fruitful source of evil.
Perhaps this will address the innate soundness of partially financing St. Peter's through indulgences.
It would also be useful to be familiar with what an Indulgence is and is not.