Frankly, if you don’t like the idea of men in the church being able to assess whether someone shows remorse for forgiveness of sins, then take it up with Jesus. He is the one that commanded it. (Matt 16, Matt 18, John 20).
As far as indulgences. It is not about a pronouncement from the church of cleansing from sin.
Indulgence is a prescription the church gives to the sick soul looking for healing. If they properly turn from sin and do the penance, the church says they can be assured of their forgiveness and cleansing.
It’s like this.
A smoker (sinner) with bronchitis goes to a doctor (church) for help. The doctor tells him to take medication A and exercise and stop smoking. The smoker takes the Meds but doesn’t stop smoking so he doesn’t get better.
That would be like someone doing an indulgence without the proper turning from their sins. If they remain in their sin, it’s like the smoker doing half of what the doctor prescribed.
Please note in this analogy, their is never fault in the doctor but everything is the responsibility of the patient.
With the abuse of indulgences in Luther’s time, it was like the doctor writing prescriptions without ever seeing the patient, or the doctor selling pills to those who don’t need it, or selling snake oil instead of medicine.
Hopefully the analogy helps you understand that the proper application of indulgences is quite reasonable.