Sports leagues are cracking down hard on athletes who look smug after making a good play.  Football:

A crackdown on excessive touchdown celebrations … has moved from the National Football League to college football and now to high school football games across the country.  In the Washington area this fall, a wide receiver from 13th-ranked McNamara was flagged for pointing to the sky after a touchdown, and a Gwynn Park defender was penalized for pointing up at the sky after intercepting a pass. … “What’s happening is in the old days, there was a certain level of celebration that was allowed. Now it’s basically no celebration,” …

There are some who view the crackdown as necessary — ridding the high school game of the scripted Sharpie-in-the-sock, cellphone-in-the-goalpost-padding type of touchdown celebrations that first appeared in the NFL a few years ago. … The cleanup of those routines earned the NFL a new nickname — the No Fun League … How far can you go before you take the joy out of the sport?…  Federation rule 9-5-1 … reads, in part: “unsportsmanlike manner … Any delayed, excessive or prolonged act by which a player attempts to focus attention upon himself.”

Basketball:

Under a new zero-tolerance policy approved by the NCAA, penalizing excessive celebrations will be a point of emphasis this season. The regulation has left coaches … concerned that one of their sport’s most marketable aspects — its raw emotion — is being legislated out of the game. …

According to ACC officiating supervisor John Clougherty … the crackdown on excessive celebrations is meant to deter players from showing up or embarrassing a member of the opposing team.  Among the actions Clougherty said will be closely monitored are pointing, gesturing …

“It’s definitely going to be tough for all the players, especially when somebody gets dunked on,” said Maryland guard Greivis Vasquez, who’s been known to be excitable on the court from time to time. “You going to just keep your emotions in or you going to say nothing? You just going to be like this [stone-faced]? It’s going to be hard.

Organized sports exist in large part to let athletes look good by winning, and to let fans affiliate with winners.  Athletes commonly call attention to their wins via trophies, rings, team jerseys, score boards, etc.  So how can it be offensive for players to have a little fun by calling attention to their winning plays during a game?

That last quote by Vasquez gets at the key, I think: when it is hard not to brag, not bragging is more impressive than bragging.   Since we want our athletes to be impressive, we want them not to brag.  We don’t mind athletes having fun, but not fun that makes them seem less impressive.