Can't roll-back every time someone writes a buggy contract. No matter how much is invested in it..
THIS is the HEART of crypto.
If he(Vitalik) does roll back, it means ETH is not decentralised..
There are literally 10's of thousands of other contracts running that have no issue at all.
I remember when the devs of Vericoin did something similar, it did not go down too well with the community.
Yes, I remember when mintpal was hacked and a large share of all Vericoins were stolen. They had to fork because the percentage of coins was so great that the entire coin would be effectively owned by the hacker.
I remember the LTC dev Coblee was totally against it and had some harsh words for the vericoin devs.