It s amazing, there are jerks in every profession, but no one is calling for a sociability test. No one threatens to not graduate a student for being socially inept. Hmm, now there's an idea. I m not saying that English is not an important skill in the workplace. I m saying that every person is different.
Some jerks write well, some nice people can t.
Maybe what we should be doing is a professional aptitude test. If a person can write well, maybe their skills should be encouraged. Maybe if a person can t write well they should be encouraged to improve them, but perhaps we should also be trying to find that person a job that doesn t require volumes of writing. I don t see what an English test is going to accomplish that your GPA doesn t already reflect. If we have to assign a number to someone to gauge their writing skill, use that one.