The fact that you mentioned your kids going to top universities is very relevant because most kids don't go to top universities, that is an exception. Another level above that are the Oxbridge universities where even academic ability is irrelevant.
What you're talking about is privilege and access to privilege. Isn't that something that we should be driving out of the system? It's not really an argument that a degree should be a competitive tool as opposed to an actual piece of usable education. This is the lie that is sold, you will get a great job by going to university, it's not true. Imagine if fees were free and we the taxpayer were literally paying to supplement this lie.
Obviously the fault lies in me for not doing well enough but we're talking about average and not the dreggs at the bottom. The average kid goes to university, comes out and doors are just not opened by default. I certainly did not rub with the highest echelons of society (except over 10 pints maybe!).
My argument is that I probably shouldn't have bothered for these reasons. I left university with a 1st degree in engineering and I couldn't get a mid-level job, I had to start at the bottom. Many others I know were in the same boat, some left and had to get jobs in totally unrelated industries where you have to say what was the point?