Although that letter is well written, I think the use of the phrases, "fuck it," and "a good wank," kind of make the parent post's point: our standard for acceptability and eloquence in language is decreasing.
As time passes what was once considered a vulgar expression (e.g., "it's" instead of "it is") becomes standard, and what was once a common expression becomes less and less used, and later it's considered archaic, and associated with culture and sophistication (because only highly educated people would still remember and use such phrases).
The net result is that what was written in a common speech hundreds of years ago may now sound unbelievably sophisticated and downright poetic.
However, in several hundred years, I'm sure teachers of English will still be decrying the decline of the English language. "Do you know what they said back in the golden days of the internet? They said 'Fuck it.' Now look at it and admire the sheer effectiveness of the expression, economically conveyed in just two words. Cannot find such eloquence these days," they will lament.
Personally, I think a reduction in average civility (especially when that civility was often masking incredibly horrifying ideas) is an entirely reasonable price to pay for the rise of universal literacy.
I consider the fact that we still teach Shakespeare in high school to be proof positive that neither teacher nor student actually understand it... if the violence and sex jokes were understood in modern terms, schools would not teach it. (I'm not saying they would censor it per se, it might still be in the library, but it wouldn't be taught front & center.)
AFAICT, neither students nor teachers are generally particularly against having racy stuff in schools -- the people that are a vocal (though often small) group of parents and interested outsiders, and they tend to be selective in their objections in a way which reinforces the idea of "bad" = "new". I have no problem believing that students and teachers could understand Shakespeare quite well without the group that is usually the source of objections either (a) understanding it, or (b) finding that it fits the particular world-view they are trying to sell to object to it.
[1] An example: http://en.wikipedia.org/wiki/Much_Ado_About_Nothing#Noting
Coding seems to be the same way. You won't see many kids today figuring out carmack reverse, for exmaple.