I'm not a big fan of text-speak on here either.
To me, an attempt to type properly and use decent grammar equates with a certain degree of maturity. It need not be perfect, but the attempt means you care how the rest of the world perceives you.
Sometimes, when I read a post that has no punctuation, no capitalization and is just one long sentence I move on, because it's just too hard to read.
It has nothing to do with level of education or so-called culture. It's just being careless about personal image!