To measure the ability to communicate successfully in an academic setting
The new test will better measure what colleges and universities need to know: a prospective student’s ability to use English in an academic setting. The new Speaking section evaluates a person’s ability to use spoken English, and the new integrated Writing and Speaking tasks measure the ability to combine information from more than one source and communicate about it.
To reflect how language is really used
The new integrated tasks that combine more than one skill are designed to reflect how we really use language. By preparing for the new TOEFL test, students will be building the skills they need in order to use language in an academic setting and communicate with confidence.
To keep up with the best practices in language learning and teaching
In the past, language learning focused on learning about the language (especially grammar), and students would receive high scores on tests without necessarily having the ability to communicate. Now teachers and learners understand the importance of learning to use English to communicate, and activities that focus on communication and integrating (combining) skills are very popular in many English language programs.
If you want to get deeper insights into it, you can check out:
What is different about the TOEFL iBT test?TOEFL Information on the Independent Writing TaskTOEFL FAQ WikiTop 10 Speaking Tips for the TOEFL iBT® TestTop 10 Writing Tips for the TOEFL iBT® TestPlease check on on my website