I think you can make a distiction between styles of writing; Txtspeak, abbreviation and slang; versus mistakes in spelling and grammar. The former have been part of English since it's been written letters and documents from all periods use such forms. To say they're wrong could be seen as a bit snobby (which has also been a part of English culture since the Saxons arrived!). After all what is to an older person, who 'learnt to do things properly', lazy is just efficient and modern to the younger people who develop and adopt it.
Mistakes in grammar are often also ways the language develops, after all dictionaries and grammars ultimate follow usage, not vice versa. For instance my personal bugbear, when people say 'less' when the mean 'fewer', is a battle now lost as the latest OED now has them as interchangeable in current usage.
Although the txtspeak misspelled examples are indeed grating, as long as they clearly say what the user wants them to they are adequate. And they don't mean the user couldn't write perfectly good formal English if chose to. I find myself vacillating between a written style and a conversationa; style when writing on the forum.
As Humpty Dumpty said, words mean what I mean them to mean.
Having said all that BHF sent out a series of emails recently advertising their charity bike rides which spelt 'pedal' as 'peddle', and I did send a proper Meldrew email back!