It beautifully illustrates different kinds of knowledge, though, don't it: it is an entirely different species of animal to have Snape say "Your father was an arrogant )(**&##@", and to see said arrogant (*&^$&^ in action himself.

Show and not tell; isn't that what Rowling is often criticized for not doing adequately? :)

What's still unresolved, of course, is to what degree MWPP/et. al. were teenage assholes, specific actions taken, motivations (I have a fondness for a kind of half-formed Vigilante!James myself), changes in character--all of that good stuff.