When you read about the History of Writing, you quickly see the evolution in communicating with written words. There are still basic rules of writing that are to be met. Often, these rules have been bent to accomodate the mechanical means of writing. However, there are still some that need to be adhered too.
Two words come to me when writing, succinct and to the point. A writing teacher asked us this question: How many words does one need to make a point? Her answer: It depends on how many points one wishes to make in the overall presentation.
Somewhere else along the line, I was instructed that the most written verbosity often had only one point, thus leaving the reader breathless with anticipation that there would be more. Alas, only to find out ...that there wasn't.
For example: Abraham Lincoln's Gettysburg Address was one point, short & profound, his Emancipation Proclamation had more words, due to being official, but none the less short & profound.
There is a divergence in oratorical pronouncements as many of us have been held enthralled to speeches that were long, rather boring and lack many points. So writing can also divest itself of any coherency by lengthy verbosity, rather than an epitome. Some of which become indigestible by anyone's standards due to the large proportions submitted. The same can be used in writing, if the writer isn't careful.
Texting is often perceived as a dumbing down of writing. The overall point in the use of texting is bandwidth and the amount of characters that can be used. It is confined by those two items specifically. The third one is the typing speed of the sender & their spelling ability. I will agree that the spelling ability of someone who texts has taken a strange turn in as much as the kiddies have 'shortened' the spelling of words and use symbols as often. It is an evolution of commmunication of writing in a sense. Writing and spelling are not static it does appear. :)
Texting to me is more like a form of the old walkie talkie. The best part of texting is that an answer doesn't have to be returned at the same time that it is received. I often don't return a text to one of my gdaughters right away, unless the message seems of some importance as in a need for an immediate reply.
All types of writing that are being done currently, texting, comments on the Internet,even articles leave the recipient free to choose when to reply. The 'immediate' need to reply is only up to the person who wishes to respond.
Writing poetry is the most succint of writing with the most points made. It is why I love writing poetry. :)