It became popular to hate on her so people jumped on the bandwagon.
If you are useless, atleast try not to be a burden especially when Humanity is at risk in a battle.
Funny you say that considering when Kaguya was about to dodge Naruto and Sasuke, Sakura punched her in the back of the head thus keeping her from avoiding them,and allowing Naruto,and Sasuke to seal her thus saving the world.
Also before then she gave Obito enough chakra to open multiple portals to farawar dimensions to get Sasuke back. Also when Naruto and Sasuke were laying on the ground unable to move, dieing from bloodloss, Sakura was the one who healed them thus saving their lives,and the world again - cause Naruto,and Sasuke were able to undo the Infinite Tsukuyomi
For a someone who is considered to be the main female protagonist in the series she recieved little to no development.
-> her combat is an identical copy of Tsunade, and even at that its a weaker version atm
-> her values have not changed since day 1.
-> she was supposed to be one of the smartest and yet turned out to be average
-> her major motivation is to catch up to Naruto and have Sasuke notice her
-> for someone who got pushed away and stabbed she sure does love him
Her values at the start was just wanting Sasuke's attention. Her values quickly changed in the forest of death when Lee Risked his life to protect, she then wanted to become like Naruto,Sasuke,and Lee,and be able to protect them.
Sakura is well above average intelligence. She made perfect grades in the academy.
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To become a medic ninja it is required to have a large amount of specialized knowledge.
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And i'm sure you know in real life it takes people years to become doctors, so for Sakura to become one of the best medics in the world on top of becoming one of the physically strongest Shinobi is outstanding.
Also, another point on her intelligence is that she made an antidote for Sasori's poisin from scratch, while even Chiyo who had decades more experience couldn't do it, and Sasori himself had extreme difficulty doing it aswell.
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And Sakura knew the good Sasuke, that is the one she liked. One of the main themes about this story is forgiveness,and she forgave Sasuke for his negative actions.