There is something far bigger than The Dao, or even Ethereum, at stake here: the very idea of immutable smart contracts. The core promise of smart contracts was brilliantly articulated by The DAO. They are designed to operate “solely with the steadfast iron will of unstoppable code.” The core idea here is that the code is the contract, and that it does not require or allow human intervention or interpretation. It is automatic and “autonomous”. Deterministic outcomes based on code — that is the value.

This value, of deterministic outcomes is 100% dependant on being able to run on a protocol that can be trusted to operate according to deterministic rules known in advance. That is what Ethereum must be. What is being now suggested is to go and change the protocol level rules, retroactively, because of an exploit discovered in one contract on the application level. To do so, would destroy the very trust that makes all contracts on the application level possible.

https://medium.com/@EdanYago/too-big-to-fail-is-failure-guaranteed-9b00a50faef1#.dxz7mwmy9