In many ways, especially for someone like Luffy, fighting with a smile and a goofy arsenal of attacks is the ultimate expression of freedom. Plus, with the addition of Gear 5, it would be weird to ...
With Gear 5 as well, no matter how dire a situation gets, Luffy can’t help but laugh and have a good time. Of the many living things in the world, only a human being has the ability to smile!
We knew Luffy was incredibly stupid but these moments in One Piece really prove it even further. His impulsive and simple nature has resulted in a lot of chaos.