It's what the balance for this game needed. Make Dragon, Fighting, and Dark less effective overall and make Steel and Poison more effective.
Since when has Dark ever been an issue? That's honestly the only thing about the Fairy type that irks me other then it needlessly resisting Bug to make it even worse of an attacking type.
The BP on Dark type attacks has never been high enough to make them threatening on the level Dragon and Fighting were and still are. Dark is also pretty terrible as a defensive typing, as all of its resists are uncommon, plus many of the Pokemon it does resist can learn something that's super effective against Dark which makes the resistance pointless in the long run.
I don't feel that it being able to hit Steel for neutral damage now is a fair trade-off at all.