Internet Speak in Essays? IDK! Common Sense?

Perhaps we shouldn't ROFLMAO about this one, because it's kind of sad. (Or can we!?) As of late, teachers are finding emoticons and acronyms, popular in instant messaging and emails, seeping their way into classroom assignments. The line between formal and informal writing is beginning to appear a bit hazy to a quarter of the teens surveyed in the study.

This issue allows for more forceful lesson-planning going forward. One research specialist declares, "It's a teachable moment...If you find that in a child's or student's writing, that's an opportunity to address the differences between formal and informal writing. They learn to make the distinction ... just as they learn not to use slang terms in formal writing."

What I see here is a lack of common sense. According to the laws of grammar, every sentence begins with a capital letter. Every sentence ends with a period. :-) is not a word, and esoteric (well, to some) acronyms are out of place in formal classroom assignments. Why can't this concept be grasped and applied accordingly? Some get it, some don't. And it seems the rest...just feign ignorance or give into laziness.

Thoughts?