<p>I think being at the level of tenured faculty can add a dimension to sophomore year-level classes and beyond (e.g., organic chemistry or quantum mechanics.) However, for intro level classes I think that research expertise beyond getting a PhD doesn’t help; rather, it is just teaching skill and effort. Some tenured faculty who are not in survival mode in terms of getting tenure and/or grants may end up being great teachers, so they may be as good as adjunct faculty.</p>
<p>And people rightly point out that adjunct profs are judged on how well they teach whereas research professors are promoted solely on their research record (unless they are at a small college.) People in academia are not immune to the carrot and the stick.</p>