She's contrubited enough to team 7s development on a whole and to the story.
Such as?
Go on, please, tell us of Sakura's contribution to Team Seven.
Or the plot as a whole.
Unlike others her develoment isnt tied to whenever Naruto needs a Tnj which was like once.
Oh, come now. Hinata (and Naruto, by proxy) changed the Hyuuga clan. The development of Hinata into a more assertive person is hinted at in the beginnings of the war arc. Her fighting alongside Neji was part of that - but the real kicker was an obscure line by Hiashi shared with Hizashi.
You see... Hinata wasn't defeated by Neji. She may have lost her match. But she did not give up. She stood, and told him that he was the one lost in the suffering and bickering between the branches. That was the moment where she solidified her growth as a character.
It was, then, Hinata, who gave Naruto the words he would need to defeat Neji, in the hours before the match began. It was this defeat of Neji that set the theme of the show in motion - that one could choose the course of their destiny (A Taoist theme, by the way).
Shame that the hyuga have not even made it into a flashback at least of the history of konaha at such a critical time of getting to know the important clans.
Now why do you think that is?
Their importance predates the Leaf Village and deals with issues before even Madara's time. As do the Uzumaki.
This will likely come of interest when Naruto gets closer to assuming the role of the Sage.
Nor will there be any time to fully develop them.
Because you erroneously believe Obito and the Juubi are the final villains.
The antagonist of the series, the main antagonist, is the nature of people to distrust each other and the cycle of pain/hatred. The answer to that will not be found at the end of this war.
Where will the manga go after these main antagonists have gone a whole new arc so we learn about the hyuga?
Come on... use your brain.
Naruto has to become the next sage, end the bickering and the fighting (at least for a little while), and come up with some kind of a solution that surpasses the previous sage's idea.
At about that time, the tailed beasts will begin to reveal more about what they remember of the Sage and his legacy. The sage, too, will probably have had a fine young lass with crazy eyes that adored him and became quite important to the Sage's efforts.
Those "crazy eyes" may very well have been the Byakugan.
"But what about the Sage's eyes!?"
The Rinnegan is based around Budhist concepts and, interestingly enough, has -not- been depicted to enable elemental mastery (despite the Sage's ability... assumed to have been derived from the Rinnegan). In line with Budhism - the Rinnegan will be revealed to be a sort of personal enlightenment that can be achieved by nearly anyone. It is not a blood line trait.
The Uchiha and Senju represent mutations of the matriarchal and patriarchal lines, respectively; possibly due to the influence of the Juubi.
The entire theme of the show is very, very Taoist. The Hyuuga embody Taoism in the show. The Uchiha were an entertaining distraction from the real meat and potatoes.
I believe the actual author of this manga has referred to Sakura as such and she will be until otherwise.
*rolls eyes*
He calls her a main character, but doesn't write her as such. She has no depth to her character, no back-story, and no real goals or ambition. The writing of her character is fickle and suits the immediate needs of the plots; else, she's simply stuck in as a passive observer, somewhere.
You could ommit Sakura from Team 7, and the entire plot of the series would still be pretty stable. She's not essential to the story. Sasuke and Naruto still have their little quarrel going on, Naruto still learns all of his techniques, Sasuke still leaves the village, Pain still nukes the place...
She was just placed as an attempt to create four wheels in Team 7. Her character simply didn't exist when Kishimoto was thinking up the grand plot (like many of the other side characters) years ago, and then realized he needed another person in Team 7 (the main team). He decided to choose a girl from Sasuke's fan club and tailor her a little bit so that people could identify with her (copious amounts of teenage girl syndrome and the hope that she'd become a tsundere).
And that pretty much describes all of the thought that went into developing Sakura. Which is unfortunate - because the premise of her character could be worked quite awesomely. But, she wasn't.
Think about it. Within the first few chapters of Sai's introduction, we get backstory on him. Sai was a little arbitrary in this regard, as he was to introduce us to Root and Danzo (aside from the creepy old guy who intimidates Hokages) - but care was still taken to give him some depth and back-story to his character.
... And as if to re-iterate how not-important Sakura is... in a movie where Kishimoto sat as prime consultant - where one of the primary conflicts of the show was Sakura's teenager issues with her parents... she goes to a world where she lost her parents and Naruto has his. And we still get no history for her.
No blissful memories she shared of her parents. No hostile memories... just Sakura being Sakura.
It's like insult to injury. Her character is just there. She appears when necessary and disappears when unnecessary without any kind of sense that she exists in a life outside of the panel she's portrayed in.