But it IS an indication of falling standards. In generations to come, people in this Country will communicate only by a series of grunts. If you listen carefully, it has already started...
People have been saying this pretty much forever. Turning is not into isn't was the beginning of the end. Informal language changes. Formal language changes much more slowly in its wake.
The mistake people are making is thinking that, because they are written forms, twitter and text messages should be in a formal register, when they're conversation, a very informal register.
If Jed spoke about the club whilst standing at a bar in the voice and register that he tweets most people would just think he was a proper down to earth chap. However, if he writes the clubs annual report in the same tone most of us would be less impressed. But I'm sure he won't.