Has no-one considered that the stock vanilla questions aren't to find out about the candidates' career/desires but maybe it's about their abilities to communicate, verbally and non verbally?
I think the bigger reason is it gives HR power over a process which otherwise they would know nothing about. By using behavioural questions it allows them to interview anyone from any technical background, while HR can know nothing about the person's area of expertise. Psychometric testing and behavioural questions just allow HR to appear relevant when any capable pilot manager should be able to hire and fire on their own.