@Mr.:
In other words, having the series go DBZ where semi-serious and more frequently goofy situations from Dragonball are suddenly serious 90% of the time and there are hardly and gag battles? I dunno, Marineford still has the Buggy antics and the Hancock gags. But that was one of the VERY few arcs that had no gag fights, because every arc before or since had at least a few between the "serious" fights, even the weighty arcs like Arlong and Enies Lobby. Skypiea was almost entirely gag fighting as was Drum island and they both sported some of the most serious flashbacks in the series' history. And what was the Davy Back fight if not just a mini-arc designed to pile on gags (save Aokiji)? In fact, I think Marineford might be the only one barring Buggy vs Mihawk and Hancock vs Smoker.
I guess it all depends on what you want out of the series. I had always considered this manga to be half gag half straight and the gag element is really what got me hooked into the series. I always thought the two elements balanced each other out–if it was too gag-based it would have worn thin eventually, too serious and I just wouldn't care because most of the drama is pretty corny (though good corn) and more "hardcore" shounens are a dime a dozen. However, the two halves play off great with the serious aspects, setting a real boffo and potentially subversive joke or gag blindside the reader when the least suspect it, and the serious aspect also allows a method to the madness, something the ground the series to the point where we can actually care about their life & death situations that is. The series could very easily have been a parody of the genre if Oda chose to do it but thankfully he didn't take that easy route.
Oda has an absolutely wicked sense of humor and really loves his outrageous gags, with a creativity in comical character designing and fantasy settings that hooked me since Water 7. I honestly cannot picture him turning this into a super serious fighting series, I imagine it would depress and bore him. Yet he does like his melodramatic set pieces so I can't see him going pure Three Stooges either (at least long-term).
Anyone familiar with the manga Kyou Kara Ore Wa? That one is very similar in style (though aiming for slightly older readers), flagrantly crossing the line between gritty real-life street drama and absolute insane gag-based comedy. I'd call it a more extreme example where "serious" fights can turn into an absolute farce at a complete whim. It even starts out similarly as virtually a gag series and deviates into more serious street grit believable dramatic scenarios.
This is purely opinion of course and I'm not trying to change your mind because I can respect an interest in the more serious side of the manga and can easily see why you or someone else prefer that over the gags.
That's not what I meant, but I like where you got. What I meant by mentioning Marineford is: Death. Only that. Death. One Piece is about pirates, about sword, about guns, about explosions. It should be about death. Many other shounen deal with the subject, too bad they deal with ressurrection too, i get it, to make it "easy on the kids", but, personally, the way Oda deals with death is the only thing I always disliked about One Piece. I'm not alone in that, I know. There should be death. And Ace died. Whitebeard died. We saw the weapons of many near their graves, so we know others died. I thought it may mean a door opening, you know? Oda just loves to make everyone die tragically on flashbacks, so why don't bring that element to the current storyline? It's always been mentioned how everything it dangerous in the One Piece world but, frankly, it isn't. Nothing is dangerous, aside from the sea. Everything is so disturbingly safe.
In this way, I don't want it to be like DBZ at all. It's the opposite. What I like in OP is that death is final. i'm not saying there should be slaughter, but I like to perceive the danger. I loved fishman island arc, because even though the fights were short and easy, Luffy was actually close to death. And why? Because of a single bite! That's how life is, screw up once and you're gone! It was awesome.
My problem isn't (and will never be) the gag element itself. It may be the time and place Oda chooses to use it, but not it's presence. Usopp's been my favorite SH because of the gag element. I've always loved his human side, his fears, his lies… I never wanted that to stop, but i've matured with the series and the characters should too. Luffy is, right now, outside Doffy's window. When would pre-timeskip Luffy do that? He would have jumped already. So even though he rushed to the palace when Viola told them about the other passage, he actually followed the strategy for the next step, because he matured. He didn't lose anything in the process. Usopp did. His comeback to face Trebol straight forward did mean him losing a little of his smartness, even if only for the moment. Even if only for the gag. And that's my problem, a gag shouldn't be used to reduce a character. You can criticize-me if you want for thinking that, but I do. He could have shot from a distance, he's a sniper…
Take Buggy as an example, since you mentioned him. He's one of my two favorite antagonists (the other being Crocodile), and that is solely because of the gag factor. I love that Buggy is still like that after all these years. He's careful, he's a survivalist, just like Usopp. And Usopp lost that at that moment, he would have jeopardized the mission and died, if not for his tendency of making ugly faces and, so, his luck.
You mentioned Drum, Skypiea and Davy Back Fight. This arc have nothing to do with those. It's a battle against one of the strongest Shichibukai. Doffy was referred as "The Most Dangerous Man". If you want to draw a parallel, Arabasta would be the best comparison. It had lots of funny moments, but mostly, it was serious businness. This one should be even more serious. Drum was to introduct Chopper. There's no way you can compare Wapol to Doflamingo. Same goes for Foxy. Skypiea was hardy, because Enel was powerful, but Luffy was his natural enemy and Enel also lacked really strong companions. Davy Back Fight was very funny, but overall was mostly... stupid and boring.
Personally, you mentioned some of my least favorite arcs. There are characters I like deriving from these arcs, but the arcs weren't nearly as interesting as Arabasta and Enies Lobby, which were more serious arcs. They were important though, and very fun. But not compelling.
Anyway, you got to a point that interested me, but I got a bit lost from my previous point: my problem wasn't the gag, is was the building of expectations! It's like a cold shower to have your favorite protagonist being built up so much for a specific deal, and then have it been done out of sheer luck. I would have loved if he had a nice fight (on screen), lost it, and then the gag moment happened. Because I would have seen the fight, I would have seen his struggles. But I'd have liked to see Usopp do at least one intelligent move, to make me believe his strategic side is still there.
So my complain is that off-screening and gags are not a good combination. They can both be done, but together they don't make the right impression on me. One thing I cannot deny: it was one of the funniest scenes on the series.
About Dragon Ball: DB has more mature content than DBZ. You can even see Bulma's nipples at some point, not to mention that she flashes her pussy to Roshi. Toriyama removed that aspect from DBZ to make it more violent, since having the two elements combined was "too much" for Jump. it's not the case here, one piece has very little fanservice, it's mostly cleavage.
PS: sorry for the big text (another one…). I'm just awful at making it simple.