I also have serious reservations about the huge penalty here, when players who engage in domestic abuse or get DUIs get a slap on the wrist.

A classic example is Leonard Little, a defensive end for the Rams who played college ball for Tennessee.

Paraphrasing from Wikipedia and some news articles:

After a drunken birthday in 1998, Little crashed into and killed another motorist, Susan Gutweiler (a mother and wife) in St. Louis, MO. When tested, his blood alcohol level measured 0.19 percent, a level considered intoxicated in the state of Missouri. Little received 90 days in jail, four years probation and 1000 hours of community service.

Six years later, Little was again arrested for drunk driving and speeding. Little was acquitted of driving while intoxicated, but was convicted of the misdemeanor speeding charge. He was sentenced to two years probation and a special condition that he not consume alcohol. Gee, why the alcohol part? And why did they dump the DUI? Maybe to save his ass from NFL trouble?

In Week 11 of the 2006 NFL season, Little signed a 3-year extension with the Rams.