Kishi intended for Sakura to act as a sort of balance within Team 7. Given both Naruto and Sasuke's extreme tragic pasts, she was meant to bring a sense of normalcy to the cast.
Her initial character design was indeed meant to be seen as annoying. She was the average girl within the crowd that treated Naruto badly and chased after Sasuke because of his status (as Kishi has stated, her love for him remains idealistic and selfish). Her gradual change in feeling towards Naruto as the story progresses adheres to the themes of the story. Unfortunately, most people took their first impression of her during her introduction and carried it all the way up until now, disregarding all of her character progression in that regard.
It is true that she has gotten little to no physical development following the Gaara rescue arc. Kishi tends to dedicate an arc to furthering a character's development, and once that is done, push them onto the sidelines once again. All the focus that he gave her post-Sasori fight essentially pertains to her bond and relationship with Naruto (Tenchi bridge, post-Sai arc, Ramen feeding scene, confession, post-Team 7 reunion, etc.).
As to Sasuke, both Naruto and Sakura must continue to "obsess" over him for the sake of the Team 7 plot. Her continued feelings for Sasuke remain as a part of Kishimoto's required love triangle. The eminent parallel to Obito and Rin notwithstanding, the current love triangle remains as an easy tool for Kishi to add significance to the bonds between Team 7 as a whole. As far as the development of this subplot goes, keep in mind that Sakura does indeed view her feelings for him in a negative light now. As we've seen with Ino's development in recent chapters, Sakura moving on from Sasuke remains to be addressed as part of her closing development.
