Daggers are useless, but they didn't make dagger backstabs inviable, it's just that they never even attempted to make backstabs for anything. Daggers have just been flawed and needed a buff and they've worked on it. It's not like people are forced to use them, it just basically meant that there was one less weapon to use. However, you could make a powerful dagger if you enchant it due to the attack speed.
When I say dagger backstabs inviable, I mean standing behind someone in sneak and attacking with a dagger, regardless of how you want to call the animation. I really hope they worked on it, and I never said anyone was forced to use them. For every "powerful" enchanted dagger, you could have a several times more powerful longsword.