admin costs have outpaced teaching costs in both total expenditure and rate of increase
Yes, when you cut teaching costs by hiring adjuncts and TAs, you still need staff to manage those you've hired and run all of the other aspects of the institution (such as admissions offices). And, counting only "costs" without looking at revenue is deceptive, because much of the revenue from students now comes in areas (such as housing and dining) that are only administrators (no faculty) but produce lots of revenue that support instruction and research.
We can say amenities will keep students away but you'd have to show me what we're cutting and is that worth the high tuition (which also keep students away) and the value proposition (also keeps students away)
If I could answer this with a simple answer, I wouldn't be poking around on Slashdot, I'd be selling consulting services to all colleges and universities that also want to answer this question. Cost does matter but amenities matter, too - and this is true in any market. For instance, a bicycle is cheaper than a Lexus, but do you want to bike in the heat and the snow and ride your bike on the highway? Some of those amenities are 'must haves,' and for many students in the middle of the market for higher education a few thousand dollars a year more in cost is worth it to have a modern place to live, something to do outside of class (like a rec center), and buildings that are not falling down; not to mention excellent food, access to counseling and advising.
I have always favored a plan that gives more options for community colleges to give bachelors and also expansion of trade schools (and treating them the same)
These are not the same at all and suggests you do not understand higher education at all. For community colleges to give bachelor's degrees, they would need to hire faculty with more advanced degrees themselves (who expect higher salaries), thus increasing the cost at those institutions. Similarly for trade schools - if trade schools want to offer bachelor's degrees, they would have to hire faculty who have the credentials to teach at the bachelor's level (which is a different credential than what is required to teach in a trade school), thereby increasing the cost.
Yes, the US spends more than many other countries on a degree, but our cost of living is also much higher than many other countries and the BENEFITS of a degree (even in $$ earnings) is higher than in many other countries, too.