You're quite right that the first two bailouts primarily rescued Greece's creditors, but Greece already owed that money to someone. The losers in those transactions weren't the Greeks - the big losers European taxpayers who adopted the Greek government's debts.
But you're very mistaken if you think that the biggest buyers of government debt are the banks. Pension funds, investment funds and insurance companies have far more cash to splash.
You're also pretty ignorant if you claim that institutions perform no credit assessment of their investments. For traded bonds like government IOUs, that assessment is essentially outsourced to three credit reference agencies, Moody's, Standard and Poor's and Fitch. Those agencies are supposedly licenced and regulated but utterly failed to identify the risk with Greek debt ahead of the downturn. If you're looking for a scapegoat on the creditor side, they're a much better scapegoat than the banks.
Blaming the banks is a lazy knee-jerk reaction that's not really grounded in fact. P.S. I'm not a banker.