Often times there is a psychological explanation for people not using specific powers. Like for example, people complained about Crocodile not trying to drain Luffy again in the tomb, but Luffy was an existence completely out of his understanding of the world, and he was perplexed why he kept standing up after getting beaten two times, even going as far as to risk their lives for somebody else, so he was shook and fed up.
But yeah, sometimes there are examples of Oda forcing characters into situations in which they suffer from stupidity.
- Luffy forgetting he can traverse the range of a huge city block in an instant against Cracker
- Kaku stopped using Soru, one of the most effective abilities in combat speed
- A lot of top tiers not using their full abilities due to plot restrictions
- Parasite obviously
- Luffy supposedly being trapped in the colosseum when he can smash the walls, and also him getting constrained by simple rope