Breaking Canon is fine, as long as it's understood or explained. 
Superman is a good example. He needs to be nerfed and to shed some of the boy scout image. 
Star Trek gets a pass since they did a reboot and put the franchise on a different storyline. 
They could do-over episode I, II and III of star wars
Spiderman should have organic web shooters 
Teenage Mutant Ninja Turtles should be aliens.... ok, not really 
To lift a name, but nothing else doesn't really work. Battleship, World War Z, etc. And I'd say it costs them dearly.