Many test-takers want to know why TOEFL tests speaking proficiency. The reason is simple. You must be able to communicate verbally at an English-speaking college or university. Also, if you are a graduate student, you must teach freshman courses. That's mean foreign graduate students must speak English proficiently. This point is illustrated in the following New York Times article, dated June, 2005. The TOEFL iBT was introduced in September, 2005. Coincidence? No. In 2005, American universities demanded that foreign students be tested for English speaking proficiency. As a result ETS changed the TOEFL CBT to the TOEFL iBT.
Read the New York Times Article