I find that many times people who learn English as a second language, know it better than those who have it as a first and only language.
DJ,
It's not only English majors that don't know proper English. I am amazed at how many middle school students can't spell. I had a student the other day ask me how to spell the word "Fight". I had to think to myself, "Didn't I know how to spell that word by the time I was in 8th grade???"
Although I believe all subjects are important in school, and granted some will be better at it than others, English is a "must". We don't have to be experts, but we should put a strong emphasis on it from the beginning of one's education.
I don't have all the solutions but think it should be given more attention than any other subject. If you know English from the beginning of your education, it'll be second nature by the time you get to college.
TIS