Wrestler and Crowd Contact

I think its more about superstars just doing it if they want to. They can't shake every hand around them, so they would have to "ignore" some fans at times because they can't get to everyone, only a few while the star walks down the ramp

I don't remember the Godfather ever really giving fives. I'm probably wrong about that though.

It's mostly midcard faces that slap hands with ringside fans and it's usually part of their entrance. The likes of Cena and Orton never do it unless it's a 'special' (like Cena announcing Bin Laden has died and celebrating with fans). Same with the top faces of the past such as Stone Cold and The Rock.