Roethlisburger got suspended based on an allegation combined with other behaviors that are detrimental to the image of the NFL. His suspension, IMHO, was very fair...Based on standards that Goodell has put in place.
Terry Bradshaw had brilliant commentary on Roethlisberger at the time.
Vilma was suspended based on what sounds like thousands of pages of evidence of something that he and his coaches were forewarned about and moved forward with anyway.
The bounty stuff might go on in secret...But when the league becomes aware of it, warns them, and it still goes on? Unless they take a very hard line, the league would be essentially sanctioning it.