@OPR:
If Doffy gets defeated like every other villain in the series before him, I'll be seriously annoyed. For the amount of the hype he received, and the stuff he demonstrated he shouldn't go down like all the other one-time villains. Not to mention the fact that Oda took the time to establish that Doffy has a close, family-like relationship with his crew not unlike Luffy's, which puts into question the reason why we root for Luffy.
- Framed a benevolent king.
- Made Rebecca's life hell.
- Turned a bunch of innocent people into toys, thus erasing them from existence.
- Island cage match of death.
- Warmonger.
- Slavery.
But hey, he likes his family, so it's ok!
@OPR:
The problem I see with how many people here view the series, is that most people consider Luffy to be the "Hero" of the story, or the good guy. I personally dislike that notion, as Luffy is as much of a pirate as all the people he fights. Having Luffy butting into other people's business and ruining everything for them just because he's the good guy is getting a little bit old at this point. I'll hand it to Oda that Luffy never said he's doing anything because it was the right thing to do, but mainly for selfish reasons, although these selfish reasons are mostly righteous ones so the problem still stands in the end.
This is especially evident in this arc, where Luffy and the Strawhats have absolutely no reason to oppose Doflamingo, except for being the good guys, and getting dragged into the conflict by Law. I believe that Oda is actually aware of this, and is going to subvert the general expectations of the fans with this arc, or at least I hope so.
Having this arc being "Alabasta 2.0" would not only be bad for the series, but will also ruin the chances of One Piece becoming anything other than a predictable shounen, which for the most part Oda managed to avoid.
Also, having Doffy easily defeated here after all the hype he received, would bode ill for Kaido, who's already being over-hyped in my opinion, and if Oda continues on not delivering on the hype he builds up for his characters, I can see Kaido becoming another disappointment added to the long list of "non-strawhats characters" who ends up as a letdown.
Luffy is the protagonist of a mostly lighthearted story. What the hell did you expect?
What do you mean no reason to oppose Doula Mongo? Do you mean characters need a deep backstory in order to oppose each other?