You had the Grim and Gritty era of comics. Wrestling had its attitude era. Gangster rap and Grunge had its hay day. trash tv became mainstream( Jerry Springer and his ilk). What happened in the 90's that turned everybody into an edge lords? I think it was essentially a backlash to the conservative 80's combined with the mainstreaming of cable(and it's looser standards) and the rise of the internet (the complete destruction of standards).
It's funny, looking back now, its crazy what kind of stuff was normal even in children's programing.
Even the commercials, were edgy. (or at least as edgy as corporate propaganda can be.)