This kind of sky high prices necessarily deprives a large number of intelligent and brilliant people from ever getting a college education in USA. This directly has an impact on the economy in the long run. Instead of funding an expensive military, US fed govt should just pay for every ones college education and recover it over the entire working life of the person in small bits. Better to have high national debt in return for an extremely well educated population instead of a white elephant of a military.
Supply and demand. The demand is extremely high, with every high school graduate being pressured to "go to college!" (to what end, few know) and student loans being so easy to get. The supply is limited, as a nation can only produce so many professors and places for them to teach.
Your suggestion "US fed govt should just pay for every ones college education" (however paid for) would just increase the demand even more. You'd still be depriving a large number of intelligent and brilliant people from ever getting a college education in USA by the sheer mass of bodies signing up - and you'd still have a limited supply of teachers & facilities, so odds of the "deserving" getting what they need remains low.
Demand outstripping supply, prices naturally rise until equilibrium. Making payment easier thru cheap debt or government handouts doesn't solve the problem because that increases the demand without improving supply. MOOCs, by improving the teacher/student ratio by orders of magnitude, does work toward solving the problem (and decreases costs as well!).