Yes there's been a number of players over the years who have earned that bad boy distinction.Can you imagine if the league had implemented the taunting rule prior to 1965? Butkus would have been pelted by flags all day long.
Remember Freddy "the hammer" Williamson who had a penchant for jamming his elbow into the top of a guys helmet. Or
Bill romanowski the master of spitting on people.
Ndamukong Duh stepping on people like they were just dirt.
Yes things have changed quite a bit sometimes for the good, other times not so much.
For me it comes down to intent on whether a penalty should be called or not.
When Rodgers was slammed to the ground by one of the vikes and ended up with a broken collar bone when he was already in the grasp that was clear intent and thus the new roughing the passer rule emerged. A good thing in the beginning but the NFL has carried it a bit to far for me now.