My objection is founded mainly through Americans... I'm a member of several baseball forums, the SI Games (Championship Manager) forums, and a couple of others when I get some time.
On those, the average age is probably 20-30, and text language doesn't happen. Then every now and again we get a wave of probably 13-16 year olds with their text message typing. Now, personally I've never made the effort to learn it, and thus it takes me twice as long to decipher their post. In the case of the OOTP forums where I do support occasionally, it's neccesary to try and decipher them, and finding the correct problem for that PC is hard enough without having to decipher the original post.
These people who use the text message typing, in general, are the same people who post 2 minutes after their original message "Why the **** haven't you answered, what a **** game", or on the baseball forums go around insulting other organisations, without any reasoning, just because the team they support recently lost to them, and disregarding the sabermetrical logic that you try and answer with.
After a while, we banned text message speaking, and I think it's for the best... I just don't see any reason for it on forums, or IRC for that matter (and the two IRC channels I use, text speak isn't used). Here it is tolerated, but I personally ignore posts where it is used, because the type of person who uses it generally isn't somebody I find is capable of sensible discussion.
That's probably prejudging people un-neccesarily, but it's what experience has taught me, and why I'm objectionable to it. When I do use SMS (My phone started with £25 credit and now has £20 after 4 months), I still don't use text language, purely because of the image I (and others) feel it portrays.
Sorry for the long answer