It's interesting that you see one of the primary motivations as competition. Is this competitiveness mostly from the administration and researchers? Who benefits from a college being better than others? Do the administrators get paid more or do the researchers get published more easily? I'm interested in how all the motives and structures break down.
With regard to your last paragraph - adult life certainly does mean very different things to different people. However, I think almost everyone agrees that financial independence and stability is important. I'm going to quote another paragraph from patio11:
"No college will actually do this (quantify the value of a degree by major) because transparency goes directly against their interests: if all degrees from a particular institution are valued at “An uncertain, but certainly large and roughly constant number”, then the standard practice of pricing them all identically makes sense."
That lack of transparency seems careless on the part of the colleges. To me, it actually seems malicious, though that might be going too far. It seems obvious that undergraduate students should be more aware of their financial prospects after graduation, but it seems like no one in the system cares.