So the intent is that a 10+ is normally success with extra candy. Rolling a 10+ should generally be great. Like if you're in combat, going aggro, on a 10+, not only do you succeed, but you also get to potentially avoid damage, kill an opponent, or something similar.
The flip side is that a lot of moves assume a risky situation. Like bending bars. When you do it, maybe you break something, or make a lot of noise. These could even happen when you succeed. So maybe whether you want to bend bars or not depends on the situation. Say you're trapped in the Goblin prison. Trying to escape probably entails some risk. Or you're trying to open the portcullis that blocks the Lich's horde. Risk is part of the situation.
On a 7-9, something bad might happen. On a miss, the DM gets to just say what happens. That sounds pretty bad, right? But the DM must still stay true to the situation. Example: you're making a bend bars move to open a sarcophagus in the old tomb. It's reasonable that you might make a lot of noise and attract a wandering monster, but maybe worth the risk. It's not reasonable that the dungeon collapse on your head killing you instantly.