Francis I of France was the first monarch to
institutionalize venality, or the selling of government offices for revenue. Those who wished to acquire social status would purchase an office and perhaps get the opportunity at some nice healthy
corruption, or the offices could be given away as
patronage (rewards to those that the King favoured).
Francis created many new government posts during his reign for the express purpose of selling them to alleiviate his fiscal problems. It is estimated that during his reign there was one person employed by the Crown for every three thousand. Obviously not all of these would have had to buy the posts, but the underlings needed a master who would pay for the office. There were also some practical reasons for increasing the scale of the government - Francis I was going through a cycle of fiscal reforms to increase his efficiency and to stamp out corruption. Although it might seem that selling offices to Noble families might not be the best way to stamp out corruption, it was generally not a bad idea.
Firstly, the Nobles and commoners (typically lawyers) who brought the offices or received them as patronage from the King would tend to be loyal to him. They would also want to be efficient because they had got the office to be a status symbol, and if they were rubbish at the job this would become well-known and their status would decline. It also meant the governemnt tended to become more specialized (you probably wouldn't purchase a post in something you weren't good at).
The problems in the long run were that the offices tended to become concentrated in the hands of a limited group of families. Over-powerful nobles, especially ones making important decisions or carrying out important tasks in government, are not a good idea. This was a problem for Francis' son Henry II and his successors, however, and in the short-run Francis gained a lot of cash to fight the evil Habsburgs.