Well, there are two important reasons: your opponent hasn't drawn their card for the turn yet (meaning they have nothing new to fight off your instant with, such as a counterspell), and if your opponent does counter your spell, it'll be on their turn, which means they tap mana
The Togglodyte still attacks since he was already declared before the spell, but it does not deal any damage
Goblin Storm Deck Description After cats, dogs, and angels, goblins finally got their turn with a Secret Lair Commander deck
I think its a very well-designed mechanic for both Limited and Constructed
This Golgari cards a mana generator, graveyard hate, direct damage and lifegain all on a body that can hit the field turn one
A strong plastic or felt deck box can help protect them from bludgeoning or physical damage when youre traveling with them