The more wealth controlled by tiny amounts of people, the less wealth for the rest of the people. It's not a very hard concept to grasp. What is stopping people from starting a business? I don't know, lack of education, lack of funds, needing to finance tens of thousands of dollars to go to college (if they can get past the terrible education they received in public school), and coming out with mountains of debt. Then these people need to go out and buy a mortgage, while currently paying the the other mortgage they have - borrowed college tuition payments on interest. Yes, the juice is running on those.
And on top of that you want people to borrow $400,000 to start a business in an economy that is struggling because of the very people you are trying to protect? You want people to go further into debt because you don't want to upset the people whose unethical packing/trading of derivatives, golden parachutes, bonuses, and poor management abilities caused the crash?
What about when it happens again?