Succeeding in an engineering career involves more than just technical skills. Behavioral interviews (aka people skills) become more important as an engineer becomes more senior. Senior engineers should have the ability to lead and influence, resolve conflicts, anticipate risks, plan the roadmap, and more.
Hiring a talented engineer that cannot work with others can ultimately be a net deficit for companies. Companies don't want to hire brilliant jerks. The company is better off not hiring a very talented engineer who refuses to work with others or causes an entire team to be unproductive. Companies want to hire the right person that will work well with the existing employees and help the team and company achieve greater heights, and behavioral interviews are one way of determining if someone will be good to work with from a non-technical standpoint.
Companies value behavioral skills and do evaluate candidates on them. At the time of writing, Facebook has one round (out of four) dedicated to behavioral interviews. Airbnb has TWO rounds (out of six) dedicated to behavioral interviews/company fit. Lyft has one round (out of five) dedicated to past experience and situational questions by a hiring manager.
- Discuss anything that's on your resume, including current projects and details
- Provide specific examples about what you did and the resulting impact
- Critique yourself and share what you learned from a past situation
- Talk about what you like about your current role and/or being a developer
- Discuss why you'd like to make a change
I really don't think one needs to attend a course on behavioral interviews, but your mileage may vary. I've seen candidates get rejected for failing the behavioral round even though they did super well on the coding and system design interviews. If you want to take a course on behavioral interviews, you can check out Educative's Grokking the Behavioral Interview course.