Actually, I don't mind the replacement of letters and numbers as much as I hate two other major break-downs(mistakes?) of English:
1. (too many spaces) Mixing up your and you're or there(comma) their and they're(full stop)
(capital A)nd (this one really burns me)(full stop, this part is largely unnecessary)
2. (too many spaces) Subject/object pronoun misuse: (too many spaces, misuse of colon, should be a small S)entences like, "They did something nice for my wife and I" should be "my wife and ME." You wouldn't say, "They did something nice for I." (too many spaces, try not to start a sentence with and)And it doesn't make you sound sophistocated(sophisticated).