I am not a native English speaker, but I have learnt it since a small age i.e. when I started school, Arabic is my first language By the way. I prefer to write good English with good grammar and not the slang English that many people on the internet use. I really feel irritateed when I see that.
I think on forums people should practice writing English with good grammar because it's a forum in the first place, so people should not be in a hurry, they can take their time in writing a post, no one will shout at them "Why are you slow D:". Actually I feel that I am faster when I write good English and not slang English. Yes, writing "How are you?" is much easier for me than writing "Hw r u"