I'll clear all the FUD : Ethereum wasn't hacked at all. That was just The DAO. There is not consequence on Ethereum at all.[/b]
Then, to reply to OP, that's quite simple : the halving. That's what's draining all the altcoins for more than a month.
So why they want SF, HF if Ethereum was not affected?
That's a kind of roll-back to cancel these transactions. Since The DAO was funded by ethers, Ethereum can do something since that's still its currency.