Earlier quoted context omitted.
Selling money is unethical because of the inherent exploitation involved, by taking advantage of someone who is in need of it. No one is saying not to make profit, just do it properly. You can rationalize interest as being compensated for risk, but it doesn't make any less exploitative. We have already seen how the economy keeps getting screwed, yet we don't learn.
"Selling money is unethical because of the inherent exploitation involved, by taking advantage of someone who is in need of it" This logic holds no water. The great majority of things sold are sold to people to need them. Why should money be any exception?
When you sell money for money, this equation breaks. You're exchanging $1 for a different amount in the future, taking advantage of the fact that the borrower cannot pay you in the present. This is what defines interest and usury.
It's easy to get bogged down in the details to legislate or rationalize a certain action. Take a step back and see the destruction that interest based lending has caused throughout history, and in the present.