Making Seth badass was a wrong move to begin with, because we had Bison, Gill and Urien. Seth was just a disposable villain that deserve to be forgotten and make way to make Bison more than he was envisioned by many before SF4 happened.
Seth deserve to be forgotten especially before SF3 timeline. Making him reappear in SFV with badass or cool persona is a poor choice.
Having multiple existing powerful organization and boss threats set in a timeline of a game where a future doesn’t even mentioned them or referenced them is a bad idea to established and just makes things more complicated.
As for Necali, is in a similar way a filler for Akuma as Seth is a filler for Bison and Gill. If even you would look into the narrative structure and how the stories is Seth is an obvious Bison filler from the connection that even Claw makes Seth feel that way in the story.
Agree that there might be something planned big with Necali but never went through because of the trailers and artwork. Which was different from Seth case that was intended to be hat even his presentation was meant to be like that.
The problem with people like cestus is that they easily expect something special to be better when someone is written feeling superior at the beginning that was seth in OAV and even in vanilla SF4 he believes himself to be something else but in games ending it is reveal that he is just a puppet and everything was planned after all.
Yes he was intended to start to that way and good and end up disposable because he was a clone and puppet nothing more that’s the surprise that even the audience and seth is involve into that even his debut in a media from SF4 vanilla and OAV lead to it because he was designed to be like that. That’s effective way if people already expect seth would survive and exist be like Bison or Gill that’s a bad idea.
That hint that Seth was disposable is his design even before the presentation unlike Necali. Along with the narrative direction in his media debuts, it wasn’t a waste potential or a mistake because he was a filler that deserve to be gone and people not to be attached to it. Lol
Since the game is set in a timeline where in the future they don’t express any threat, power or danger. Bison is just worth saving for the future games for being the most iconic boss character and well established. His the Ganon and Koopa of SF universe.
Some boss just need to be fillers, uncool, annoying and not compete with attention the current iconic bosses. SNK did well on those with the NEST saga.
Imagine making cool and badass filler character that was hype up with the same appeal as the iconic ones so as a result people would be divided into future polls and character request of would be bosses. Even they were killed or supposed to be not existing anymore. That make Necali compete against Akuma and Seth would do the same with Bison and Gill in future interest if they are presented as better characters that what they ended.
So taking them out of the picture as simple but storywise way as delusional meh bosses that just has resources and powers but never became a direct threat ot memorable to anyone else that would have potential to exist in future SF games was a clever idea that Capcom pulled off.
So this makes both Akuma and Bison extra ordinary, exceptional and superior not just a guy with instant kill moves, mystic powers, organization or got resources.