This mechanism -- purchases of senior preferred stock with warrants in troubled institutions -- addresses the problems with the Treasury plan. The financial market is stabilized, companies get recapitalized, failures are avoided, debt securities are supported, and time is gained for illiquid assets to mature.
The institutions continue to function, their cost of funding will decline as equity capital increases, and innocent third parties like bank depositors, broker/dealer clients and insurance-policy holders are all protected. The only difference is that potential losses are kept with the shareholders where they belong.
Under a Preferred plan, the shareholders of the firms who created the problems bear the first loss. Who do you think should pay?