Board Thread:Naruto Discussions/@comment-33731988-20180116041116/@comment-26947865-20180116151239

It comes from where exactly she's positioned in terms of the plot. She's on a team with the two most powerful shinobi ever seen, so the scale used to define her worth is tipped heavily against her. This is also coupled with the fact that she has multiple "I can finally stand with them!" moments which are immediately followed by one or both of Naruto and Sasuke dwarfing whatever she just displayed.

So no, she's not useless, she's currently Konoha's best healer and arguably one of (if not the) best kunoichi in the village, but she's held to the standards of the original Team 7 which she couldn't hope to match.