Disregarding the limit rule.
This man essentially has it correct. Most people get turned off by the art style and think it won't be good. I, personally, think these people are close minded to not watching anything that isn't drawn in the 'generic' fashion of anime.
For example, the character Usopp has a long nose, tan skin, curly hair and much skinnier than your normal build. Plus his face is more rounded, he has nothing but a dot for an eye most of the time.
Oda also brings back the traditional Hour Glass shape to the some women that has been forgotten for detail body and creases.
He also has mythical characters that seem more cartoonish or a exaggerated to give off better features. He draws most animals different from what normally would be drawn.
Also, his characters aren't pretty boys like the generic scene. They have a certain taste to each of them that is different from the previous. As such, Admiral Garp and Luffy differ in almost every aspect of their body type. Garp being more top heavy and luffy being more low heavy (at the beginning at least.)
Development is also known in the One Piece world from maturing, attachments and where peoples trusts lie. One example is that Usopp, even after traveling with Luffy, still has his loyalty to the people back home above all us.