It hasn't been FoW or bust since Mindbreak Trap was printed. That's a reasonable combo counter. So is Flusterstorm against anything but a turn 1 kill.
If Misstep only hit instants and sorceries, it would still be good but not stupid. I don't mind seeing Misstep hit Ancestral. I really hate seeing it hit Thoughtseize, but whatever. The real damage is to creatures and 1 drop permanents that had a place in the format and no longer do. Mana dorks like Hierarch and Deathrite are practically unplayable because getting your turn 1 play tempo'd is backbreaking so often.
I really, really loathe Misstep. It's interactivity of the worst sort. At least a Chalice you can play around and remove to unlock your hand.