Not repaying a debt is also morally wrong: you needed the money and said loaner felt morally obligated to help you out. You took the money on his / her terms. You are now beholden to those terms whether you believe in morality or not. Morality will continue in the world with or without you.
You can dance without a lawyer
The reason contracts are needed at all is because of the views presented in this thread.
Of course no one should have to repay a loan. I say just grab the loot, and the fool of a lender be damned.
“I think if Thomas Jefferson were looking down, the author of the Bill of Rights, on what’s being proposed here, he’d agree with it. He would agree that the First Amendment cannot be absolute.” - Chuck Schumer (D). Yet, Madison and Mason wrote the Bill of Rights, according to Sheila Jackson Lee, 400 years ago. Yup, it's a fact.
I'm sure you base some moral decisions on the person and the situation being dealt with.
Take killing people - I'm sure you think there are certain situations and certain people where it's moral to kill them and other situations and people where it's not OK.
Your pretense of moral superiority is laughable because your position is so far removed from morality that you have to argue that morality is completely independent of reality.