Swords haven't ever been nerfed, but you don't see us charging into war with them any more.
The rules are changing, and your opponent, who may not use the cards that are hampering his mulligan chances, will benefit from the change while you do not (if you use those cards).
That being said, it's not a very big difference. I mean, i'll still use cremates and RoLs and kami can keep using daggers, since he seems to think they're not terrible, and for the most part it won't make any difference at all.