I second solax, the only time I find it okay to stop saying gg is when I am with friends. If you want to show some humility and respect, gg them for sure, but not saying it also does not make you any worse. If, however, the other player is saying gg, it's good to be mutual so that you do not come out as arrogant.

It kinda depends on the person for me. Most people I know say gg if the game was actually good, and I typically do the same. However, if I'm playing against a new person, then that relative "good" suddenly becomes much lower. So against new players I'll typically say gg even if the game was outright terrible (I typically wait to see if they say gg first for those though).

It's not a big deal and I don't see why people make it to be a big deal. I think if you actually managed to write a whole paragraph about two letters (let alone make a whole thread about it), then you should find better things to do with your time

I say geegee regardless of the quality or outcome of the match. Unless, as erf/Solax stated, the other player is a close friend; then I usually call them a scrub.

You don't have to call gg, but don't be rude to other players.

In general I won't call gg if I didn't enjoy the game, and I won't call it if the opponent bm's or calls winner's gg before the loser calls. If loser doesn't call gg first then I won't call as winner.

There's no need to go around calling gg, so just call it when you honestly feel that it was a good game.

I just type GG..
Why not, why shouldn't I.

if you dont say GG, a russian granny will find your house, burn it, find you, blow your anus, i saw that.

I guess it just depends on what kind of player you want to be.

I say gg if I honestly believe it was a good game. It doesn't matter if its against a white belt that JUST got the game. If we played and he/she isn't an asshole I'll usually say it. On the other hand, If I miss-clicked through the entire game (which happens) or the other person is an asshole, I won't say it and usually state why.
If its a person I respect, I'll usually say it regardless.

I don't like it, but for showing my respect to my oponent I type gg, 'nice game',...
Although I won't do it if my oponent would lift, shovel, gay style, etc