User blog comment:Fintin/Doflamingo's Survival and Bird Cage/@comment-3273232-20140412091558/@comment-1595565-20140418001942

Usopp is the only character in the crew whose strength is comparable to an average real world human. Everyone else is superhuman by real world standards. It's to give the series some perspective. He will always be the weakest, whether you like it or not. He's not powerful and he never will be how you want him to be because he's not supposed to be. And the mind-changing you're banking on doesn't happen this far into the series. It happens during the character planning stage, which happens before the character is introduced.