Home mortgages have real estate collateral behind them. Unfortunately student loans are not only uncollateralized, but they have pretty high default rates that are covered by taxpayers. Also unfortunately, no one separates medical student loans from other student loans, so we are actually subsidizing defaults by students in other disciplines, since med students have very low default rates.
If there was no taxpayer subsidy and the program was expected to be self sustaining, the rates would be FAR higher than they are, and we'd all be taking private loans. Private lender rates are exactly where they should be, since no one has to take them, so they are truly market based, determined only by a lender's loss experience, their need to make a profit, and what the market will bear, given that there is a federal alternative that is available to all of us.
Private lenders do, in fact, have relatively attractive rates for med students, but with them you give up things like income based repayment plans and PSLF. Pick your poison. The good news is that you are eventually going to be in the Top 1%, and you WILL be able to pay back whatever you have to borrow!
As to why their aid sucks, the answer is that they just don't have as big an endowment as other schools. They are expensive because they are private. Their tuition is in line with most other private schools.
At the end of the day, your reaction is not atypical, and is why they have a ton of WL movement every year, even though most people agree that it is a great school. They don't do merit scholarships, their need based aid isn't great, and they are not quite T20. They end up losing a lot of people to less expensive and/or more prestigious options. And they replace them with a bunch of people eager to take their place. Every single year.