User blog comment:Keekian/Will OP be better if Luffy was smarter?/@comment-26058050-20170417122310

Luffy's "dumbness" is 90% for comical effect, and 10% is human nature. If you go over the series you'll find that Luffy is actually quite smart and will often know exactly what to do or what to say. A classic example is when he stops in the middle of the desert, just to make Vivi realise that she doesn't have to do it all on her own (after getting punched in the face). I can think of several others including letting Bellamy beat him up with no resistance, purposly fighting Lucci knowing that no one else could defeat him, even discovering how water (and later blood) can help bypass Crocodiles powers.

He may be childish, naive and an overall idiot, but he's certainly not dumb. He's just not a strategic thinker like Sanji or Law