The odd 'u' instead of 'you' or '2' instead of 'to' is ok.
I can think of three reasons why text speak is 'morally wrong':
1. It's difficult to read
2. It cheapens the forum.
3. It makes the writer look like an idiot that hasn't mastered the basics of the English language yet.
(Also text without any punctuation, or line breaks, whatsoever - you know who you are
)