Question on revertability of the Ethereum chain

Suppose there is a 51% attack on the Ethereum blockchain, and because of this attack transactions get reverted. Is it not interesting from Ethereum's point of view to implement a protocol rule which essentially would prohibit any reversions of the blockchain even in the event of a 51% attack? Would this immutability make Ethereum not more interesting from a security perspective?

May be a stupid question, but I was just wondering. 🙂