I agree that scripted interviews can be boring... but it's not just common wisdom that using structured interviews leads to better assessments, there's plenty of research* that shows that too. Of course, you should always take research in this field with a grain of salt, since things are different from industry to industry and company to company. But I think it's safe to assume that unstructured interviews are more prone to unconscious bias. Research also shows that most people think they are better at assessing candidates in an unstructured environment than they actually are. If you're really experienced, you might be calibrated enough to be immune to that to a large extent, but it's still hard.

But yeah, I agree that it can be boring and a poor experience for both candidate and interviewer if interviews are too scripted. It also has other failures, e.g. it can fail to capture different talents that candidates might have. I personally think the best way to handle this is to mix both structured and unstructured interviews.

There are plenty of other ways to make interviewing rewarding. Think of it not as a burden, but as a way to help both the company and the candidate make a possibly life-changing decision as accurately as possible. Empathy can go a long way towards humanizing the process. Honestly, one of the most rewarding things I felt as an interviewer (and then a manager) was seeing someone I interviewed (or hired) later thriving in a role. Being a part of making that happen is really fulfilling.

* http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.172...