Tbf, that's Oda's imagination doing overtime. Reed Richards never gets past the Gum-Gum Pistol stage, I think his power would be considered way cooler if he hit Dr. Doom with a Gum-Gum Elephant Gatling or busted out Snakeman. It's not just about making them a serious main character, mangaka seem a lot more inventive with utilizing the potential for powers than their Western counterparts.