"I think that is a rather harsh and cynical view of Luther."
I don't see how it can be considered to be a harsh and cynical view to say that what began as a concern over something that pretty much everyone knew was wrong (the sale of indulgences) quickly expanded to a very radical change in virtually every aspect of Catholic theology.
I'm not defending medieval Catholic theology. I'm just saying that if one wants to defend Luther, one must defend most of what he changed or tried to change, and not just keep drumming on the sale of indulgences -- something that is non-controversial in the extreme.
Indulgences was only the external example to an internal doctrinal problem; works verses faith. The Church had reached such a point that examining relics, paying money and pilgrimages would lessen your stay in purgatory. There is no basis for any of this in scripture as Luther discovered. Man isn't saved based upon pilgrimages or relics. Man is saved by his faith in our Lord Jesus.
And where does staying in purgatory pop up? In some obscured verse in the Apocrypha that the early church fathers agreed was only a historical document. Sorry, but I think there is sufficient evidence of a corrupted theological system-and I'm not saying this simply because I'm a rabid Protestant. The Church had totally lost its focus on God's grace.
You may say that wiser men throughout the ages made "reasonable" assumptions based upon their interpretation which the majority of people agreed with. I would say the majority was in error based upon flawed interpretations developed based upon their environment at the time. Error compounded upon error warped God's Holy word until He brought about the appropriate situation.