Why does nobody say 'good game' anymore?

Because ppl are buttholes.

Win or lose, I say "good game" 99% of the time.

Just a few exceptions:

1) if they promote their pawn to a rook or something just to be a jerk

2) if they don't even try to checkmate me and just try to promote

3) if they post obnoxious emojis to taunt me

If I win and say it, I get a "good game" in response maybe 5% of the time.

If I lose and say it, I get a "good game" in response maybe 20% of the time.

If I'm playing someone in India, win or lose, I've gotten a "good game" in response 0% of the time. No idea why. 

Maybe the game wasn't good?

Whether I'm playing in a tournament or in a casual game, as long as the computer gives me the chance I always click the link that says "say 'good game' to opponent".

I think people have just forgotten the traditional rules of the National Chess Federation that say always say "good game" and shake hands before and after game.

Uhm that's bc ppl leave as soon as they finish a game or they start a new game so there's no point

It's not the point of needing to hear the words, but it's just polite and sportsmen like to say them. 

I'm afraid its true. Blitz is just too fast and, especially in 1 or 3 min. games, some players will get on a "hot streak" and not want to break for even an instant. On to the next game!  But I agree with others here that in a 15 minute or longer format, saying "GG" would be the more civil approach.