Our school was one of the more expensive public schools in the country. Since the state reduced funding exponentially over the course of a few years, tuition was more similar to private, and to make up for it we started enrolling a lot more OOS students who pay similar to this. The state legislators' collective response is simply: supply and demand. If you have no lack of qualified applicants, just charge more to make up for budget deficits.
As long as students are dumb enough to pay that much money (especially when there are 5 other CA schools with potential plans to open more, and neighboring AZ, UW, OR), USC has no incentive to maintain or decrease inflation on that tuition. I'm not sure if ADEA makes schools justify their tuition/fees, but I assume they have to for accreditation. So I would expect that conversation to continue.
No, a 4-year dental education is not worth $500,000 unless you have Uncle Sam paying or a rich grandparent trying to reduce their inheritance tax burden. You'd also be stupid to pay that much and then try to find a job in a saturated area like LA, SD, or SF. That's financial suicide and patients will ultimately suffer from over treatment and creative diagnosis.