If we're talking about the English language as a whole, then yes, I believe that texting, and texting lingo are bad for the language. The proof of this is in our modern English-speaking society. Colloquial English has seen more adaptation recently than ever before, and this includes the shortening of words and phrases in both spoken and written media. The standards that are used in texting are nowhere near the acceptable standards that are used when speaking to someone directly, or writing in a professional matter.
While many people are proficient at texting using lingo and speaking/writing in a professional matter and keeping a distinction between the two, too many people are blurring the line and speak to people as if they were texting.
A big argument can be made that texting can also make people socially inept, and will not make eye contact with others when speaking to them, and will say considerably more if it weren't in a face-to-face basis.
My argument is this:
Overusing text messaging will lead to poor grammar overall, and will also lead to the degradation of social skills that are needed in the real world.