I expect the fact he's just beaten Federer, arguably the GOAT, is reason enough for such a celebration. I am a big Federer fan, but I have noticed a slight touch of arrogance creeping in to Federer's demeanour lately, so maybe that plays a part. But I don't think the wild celebrations are just reserved for Federer, having seen the shirt ripping at the AO.
However, one of the many things I do like about Novak is how he congratulates those who beat him, with a big smile and hug. Watching Murray at the USO, crouching in a state of shock, having experienced winning a first slam before it was nice to see Djokovic walk around the net to congratulate Murray.
I guess you also have to think back to what Djokovic was doing when Federer started his domination of the game.....he was just a teenager watching Federer on tv, wondering if he would ever get to play him.
"Tennis is just chess with balls....zugzwang"
"The older I get....the better I was"