Yes, it is very important for all American universities to ensure that all of their students are fluent in written and spoken English, and this may require more stringent testing of English skills prior to admission. Although there are many talented students who are non-English-speaking, it is impossible to facilitate higher education without a common linguistic base.
I think the English Proficiency tests we currently have in place are doing the job just fine. If foreign students are not worried about their communication level, why should we? Living in the United States will teach them English Proficiency more quickly than any other English lesson they will ever have.
When attending colleges, there are many different time in which you must demonstrate your ability to read, write, and comprehend. This means that if a foreign student were to go to college and submit grammatically incorrect papers or not understand the lectures, their grades will reflect this. It should be on the student that decides to go to a school that teaches and learns in another language, to be prepared to use that language.
The litmus test to see if a University or any education organization had done its job will always be the student. The student's ability to acclimate to the work environment and use his/her skills to join the workforce is the contributing factor of how to judge a University degree. If a student's ability to communicate is poor, then it first looks bad on the student and then the University if it prevails through many students. If the University sees a general lack of foreign students' abilities to participate as an effective employee, then the University should alter or enhance its curriculum accordingly. Other than that, the student has the ultimate right to concern themselves with their ability to communicate through English because not all foreign students seek jobs in the US.
As long as foreign students can pass the standard English test that every American must past, then that should be good enough. Why are we going to make foreign students have to go above and beyond what everyone else hast to do? This country needs to keep an even playing field across the bar.