I really don't think people are overreacting at all. The card is sick. Seriously every deck in legacy has 1 drops except Chalice decks. And as a point of fact, every deck in legacy has 1 drop cards it hates seeing and this is just a versatile answer to all of them.

Look at it like this:
Control Matchups:
Combo: stops at worst cantrips to dig, at best stops High Tide, Dark Rit, Duress, Chant and the list goes on
Non-Vial Aggro: Stops one drops like Nactal and Lynx that can get in a ton of damage if not answered right away, plus isn't really dead late game as they have to keep playing dudes.
Vial Aggro: Probably the weakest here in terms of what it hits but its also FoW 5-8 for their best card against you - Vial.
Tempo: Stops near 50% of their deck. Awesome.

Combo Matchups:
Control: stops Snare (maybe) and opposing Missteps as well as Top. Not that great
Any Aggro Deck: Stop Vial/Nactal/Lackey/whatever is going to give them a chance to race you
Tempo: Stops 50% of their deck which is nice.

Aggro Matchups:
Combo: Gives you a chance to race by stopping a critical Dark Rit/High Tide/etc
Control: Helps fight removal so your dudes can get in for more damage
Aggro: stops vial in vial mirrors and stops opposing removal to allow you to win creature wars.

So of the three big pillars of Combo, Aggro, Control, everyone has a pretty big benefit to playing misstep. Combo probably has the least to gain but if everyone else plays it they kind of have to.

Also, saying the meta will shift away from one-drops really isnt fair. For one, combo just can't do that, and for two, if you are a deck that is less reliant on 1 than you are either a Vial deck or a Chalice deck