I was just thinking about this the other day. I am one of those people who will type out a text and use 'big' words on purpose. My kids do not have cell phones, so they aren't as affected by this issue as other kids, I think, but they DO play some video games that encourage texting while playing, and from these they are learning 'words' like 'brb' 'LOL' 'totes'etc... and they pop up in every day life. It hasnt really been a problem yet, but I HAVE noticed in general, when people write on social media, (or anywhere else), the general vocabulary seems to be shrinking and people just arent able to paint pictures with words the way they used to...
I think we are fighting the current here, and this will continue to get worse over time, but all we can do is use proper language ourselves, and teach it to our children.