There's been a discussion on Meta.SO about this for a while, and while there are some conflicting opinions, the general consensus is that these are unnecessary noise and should be removed. I wouldn't go ahead and remove them with impunity from older posts, but would do if I spot them on new questions.
As far as excuses for poor English -- SE sites are collaboratively edited, including questions and answers, and virtually all questions asked are improved after the fact by people having better command on the language, including grammatical, lexical, vocabulary or punctuation errors. So these excuses become obsolete immediately, and should be removed.
From personal observations, the presence of salutations is somewhat correlated to question length and quality. My guess is that the OP tries to "inflate" the question length to look worthy of being answered, while omitting potentially useful information. I think one of our more pressing mid-term goals should be to not only increase the number of questions, but also their quality, by "educating" the users and even being slightly more strict about what kind of questions we want to see here.