Becoming a homeowner is still a vital part of building wealth in America. However, qualifying for a mortgage or obtaining the money for a down payment is still too difficult for many poor and lower middle class people to do for a decent home.
Creating a legal structure wherein a prospective homeowner could purchase 50% or 25% of a home, while paying rent on the rest, would be beneficial to everyone involved.
Smaller mortgage amounts widens the pool of potential loan recipients, without hugely increasing risk (unlike the derivatives market), creating entirely new markets for banks and a new ways for charities and non-profits to help lower income families. Neighbourhoods that are currently dominated by rental units would benefit from residents gaining an interest in their home values.