One problem is that the deposits are not allocated well. Banks have enormous amounts of capital to manage, thanks to government guarantees, and extract a lot of fees from those deposits and then lend in destructive ways. If German and US can't think of anything better to do with capital than speculate on bonds of nations that obviously will not be able to pay back or US mortgages, then perhaps there should be alternatives.

I'm not proposing outlawing private banking, just providing a baseline safe government alternative.