My guess: it's due to texting and various online social media sites like Facebook and Twitter.
Basically we have two groups of members here: those that grew up before texting and Facebook and Twitter, and those who grew up during texting and Facebook and Twitter.
Those of us who grew up before the internet came along learned correct spelling, grammar and punctuation in school, and we apply what we learned (at least most of us do) in our written communication, becaue that is the "proper" way to communicate. It was expected of you, and if you didn't, you were considered to be less educated.
Those who grew up during texting and Facebook and Twitter also learned correct spelling, grammar and punctuation in school (I assume)... but because the communication outlets of today encourage abbreviations, acronyms, slang and such, they tend to communicate in that way. To them, correct spelling, grammar and punctuation are basically irrelevant. It's all about being "cool" and using the latest new lingo.
It's a generational thing. And personally, I think we've dropped a level or two between generations.