Perhaps nursing could be used as a case in point? I'm not sure if it has happened yet, but haven't the government said they want nurses to have degrees, too? Now that might seem crazy because a nurse is a nurse, right? But perhaps it isn't as simple as that, perhaps nurses now have more expected of them than nurses of old?
I can't really comment on that, but all I'm saying is that it could be a reason for this change. It'd be interesting to have a nurse's input, tbh.
Quite possibly.

I was thinking more to do with the generic base level jobs that now need a degree level candidate, where before they would have just hired someone with decent A-Levels, or even GCSE's. The fact that any degree level candidate will do seems to indicate to me that the actual degree isn't really important. Also the number of people that apparently cant progress in a company after a few jumps because they don't have a degree, again generic degree is fine so it's not about the subject studied.