I have a B.Tech in Electronics and Communication. The courses I loved the most in college were all humanities courses! Of course, correlation not causation etc. applies here.
As I wrote in another answer (link), if you understand people, you can do product thinking. Humanities definitely helps with that.
I don’t think it will ever become a hiring parameter, given the dearth of great product managers. However I strongly believe it will help good PMs become great. I wish I could establish through a series of logical statements but I can’t. And hence it isn’t a hiring criteria either.