Quote from sjfan:
I think your belief that bank == the middle man is faulty. In many ways, banks function more as a conduit for risk-pooling rather than just intermediation. Think about it this way: individuals dont' have the time or the expertise to diversify their investments across many different ventures such that the risk to one default is small. Banks, on the other hand, can. Through specialization as well as risk tiering (the bank's own capital is the first piece suspectible to losses [and in the absense of depositor insurance] and the depositers' are the last-to-lose piece). This waterfalling of losses cannot be constructed without a risk pooling entity like a bank.
Moreover, I take issue with your notion that banks do more harm than good. We can readily see that through a web of regulations a perverse web of disincentives have created some problems, it's hard to imagine how modern capital allocation can work effectively without banks.
For example, assume you are really good at making Wedget A. In fact, you are the best and the world is willing to pay you for Wedget A. You grow rich. However, you now have to decide: you can continue to make Wedget A, or you can spend time working on your investments so that you don't lose your wealth due to inflation or opportunity cost. You'll have to fly around and interview different firms and working on various asset allocation decisions. However, you aren't very good at investing (or rather, you are much much better at making Wedget A). In a world without banks (and asset managers, etc), you will have to forgo part of your speciality; overall, society losses from the lost productivity;
Moreover, under your proposed system of bankruptcy insurance for investors, incentives will be as such that everyone will take very high risk ventures: heads, shareholder wins, tail - the population losses.
Not to mention everyone will get married (if only on paper) the minute they are allowed to do so to maximize their "household" share of the economy.