I think the markets will work for the average person if they give it enough time. I also think doing research and seeking professional help advice will also greatly aide in the success. Individuals are going to have to take some time to be successful. They need to read and learn all they can.
The average person who is looking to invest in the growth of the US stock market can do so now with very little risk of principal loss. By investing in indexed funds the "mom & pop investor" can get the advantages of professional research and stock selection without putting up big money or take huge risks.
I do not believe that the financial markets can benefit the average American citizen anymore, largely because of our culture of debt. The average American carries too much debt to make meaningful, consistent investments. Our nation owes too much money to other countries, and must pay those debts or sell off our nations assets in order to pay them.
No, the markets are not designed to be accessible or affordable to the average person. The majority of Americans are not educated in the economics behind capitalistic market systems. The information available freely is either too vague or overly esoteric, making it difficult for anyone to participate without the assistance of a knowledgeable (and expensive) adviser. Brokers, supposed advocates of the average person, are themselves the hoarders of stock knowledge, manipulating the information they supply to fulfill their own agendas. The market is about making money for yourself, and thus, no one involved in the process can be trusted. Additionally, the financial costs between hiring a broker and the inevitable risk of loss along the way, make it difficult and cost-prohibitive for the average person to justify the investment.