One of the advantages to reading literature from the past is that it can give us a perspective of our own lives from our 'blind spot(s)'. I may not understand the significance of the finer detals of the practices which Luther was questioning at that time but I can gain from his warnings an insight into human nature and its tendency to attempt to cloak avarice in good intentions, its tendency to prey on the weak and trusting, and its general censorship of those who do not accept the status quo (to mention but a few).
I do not mean to say either that these tendencies are only present in others but rather since they are a part of human nature, all humans have the seeds of these tendecies within their hearts (and 'all' includes me). Therefore we must guard against similar corruptions (hiding in modern clothing) both from without and from within our own hearts.
Another little lesson to be gleaned from reading a few of Luther's theses is that humour can be effective in both softening the blow and driving home the point:
27. They preach mad, who say that the soul flies out of purgatory as soon as the money thrown into the chest rattles.
28. It is certain that, when the money rattles in the chest, avarice and gain may be increased, but the suffrage of the Church depends on the will of God alone.
62. The true treasure of the Church is the Holy Gospel of the glory and grace of God.
63. This treasure, however, is deservedly most hateful, because it makes the first to be last.
64. While the treasure of indulgences is deservedly most acceptable, because it makes the last to be first.
65. Hence the treasures of the gospel are nets, wherewith of old they fished for the men of riches.
66. The treasures of indulgences are nets, wherewith they now fish for the riches of men.