One of the main reasons language teachers are adopting CI-based practices, is because it creates an environment in which all kinds of students (especially marginalized students) can be successful, without compromising proficiency goals. Here is a collection of links to articles and blog posts which elaborate on this important connection.
Stephen Krashen addresses the problem with viewing language learning as skill building with delayed gratification:
Non cognitive skills. Their role in academic success:
Stephen Krashen on teacher activism: