I like usopp, but his gag isn't really that funny. While sanji/zoro/chopper/luffy/franky and even Nami have a good running gag and is used well, ussops "i'm a coward" is bullshit.
Because he already "overcame his fears" like a hundred times already. Shit there was a time where he fought Luffy, the fucking captain! He became the goddamn Sogeking! He's always cowardly, but he'd never just ditch people like that!
Now it seems he's somehow reverted to his almost original form, waaaaaaay back on the damn merry-go Island.