Because the Soviet Union's state-run banks served the little guy so well. The reason the "little guy" gets poor service is because the risk profile is extremely high for the return; however, micro-lending is filling in some of that (see http://kiva.org/, for example).

The use of the financial sector as a political weapon is concerning (but that is more possible with state run financial institutions). I'm not sure how you prevent that without basically allowing mega-corporations to be above any national laws.

What we really need is an international court that can arbitrate these kinds of disputes.