Literacy in the data center? Among the Turing machines? They ain't English majors, you know!

They doan need no stinkin 'postrofes!

Competency in natural language is, sadly, no longer a requirement for graduation from the Eighth Grade.
Reading on-line newsletters, email, forum posts, and even blogs is often an exercise in frustration, if not an outright invitation to violent fantasy towards the author.
I find it very strange that native English speaking programmers who go to the effort of learning the most obscure aspects of C syntax can't be bothered with observing rudimentary English grammar when writing. Language is language whether it is C, ASM, T-SQL or Farsi.
Writing poorly in any language is often a sign of sloppy thinking and poor organization.
Poorly written code won't compile, doesn't work as intended, or possibly opens yet another avenue for exploits into the target system.
Poorly written natural language, English or otherwise, detracts from the point the author is making; as well as diluting the effectiveness of their argument, which might otherwise be convincing.
English wasn't my major, neither was CS, although I ended up writing code for a living. Writing well in any language is worth the effort required.

My personal pet peeve is the oblivious misuse or confusion between
"they're" - contraction of "they are"
"their" - possessive form of "they"
"there" - an adverb or pronoun depending on usage.