Honestly it really isn't. The only reason you think people are much nicer in this game is because SE holds a gun to their head telling them to be nice.
If by that you mean the TOS and codes of behaviour are enforced, yes they are, and glad I am of it. See, I dont need to worry about the TOS, I dont need to be told to mind my manners or not swear and scream at people, I already know this, as thats whats called civilised behaviour.

Recently I saw someone comment that why should they not be allowed to swear as 'theres a filter", it really comes down to this:

If whatever it is you want to say cannot ever be said to that persons face, then dont say it. Treat people with basic common decency and kindness, practice some tolerance and a modicum of patience and as my own mother ( Love you to bits, Mum ) taught me, self control and maturity means knowing when to hold your tongue.

Treat people as you would wish to be treated yourself, think before you type, when in doubt, take two or three deep breaths and count to ten. Then comment in a calm and measured tone, which, trust me, will be a huge improvement on what you wanted to say originally.