Couldn't agree more strafer. Trouble is, just as it is easy to way someone up down the pub (or in an interview) it's just as easy for them to be on their 'best behaviour' because they know they are under scrutiny. Think about it, do you bare your sole at interview so they see the real you, or do you paint yourself in the best possible light, only showing them what you want them to see?
Don't get me wrong, I'm no particular fan of this type of thing, just that it's their train set and in order to play with it I have learnt that you have to go with the flow. Understanding it is the key, then you can at least exert some form of control over the situation. What they are trying to do is find the 'real' you; what makes you tick and as you say, just about all big business is using these techniques these days. They use them because they get some form of return; they like the 'product' the process produces. They wouldn't waste tens of thousands if they didn't see a value in it.
I also agree that I am sure there is an element of self justification in it for HR types, but the underlying principles of it are based on some form of fact. Just look at the extrovert / introvert that we have all heard of. We all know these two types of characters and have met them over the years. I have met people who were so introverted it stood out like a sore thumb that they would be totally unsuited to the role of commercial pilot, funnily, one of these characters was training for a licence.............. Perhaps the recruiters could save some money there and just take him down the pub for an hour or two!?
PP