It costs a lot less to save a small bank than a big bank, and the risk is spread out over multiple organisations. If we had (for example) small banks that were

It costs a lot less to save a small bank than a big bank, and the risk is spread out over multiple organisations. If we had (for example) small banks that were more specialised, if the housing market falls through, those sorts of investment banks would disappear, but others should stay relatively untouched. That was the whole point of Glass-Steagal : if the investors mess up, at least make sure that we don't have to wipe out Grandma's savings.