>>56676246As a Sakura fan myself, more or less true. She had a lot of potential and the very few times they let her be a more rounded-out character are fantastic, but it always returns to the status quo and ruins any chance of being better. I still think they're more interesting than generic waifubait barely/non-characters like Hinata, but they're extremely polarizing.
The archetype, so to speak, fucking sucks and visibly holds the character back but considering that authors like Kishimoto really can't write female characters well at all, I'd say she fares somewhat better than others who were made to be badass and turn out to be nothing burgers.
I can't really speak too much on Serena, since I skipped most of the Ashnime, but the little I did see painted her as a mostly flavorless character who, like you said, lived and died by her being Ash-adjecent. The new anime isn't anything to write home about, but at least I feel the character philosophy in general is a smidge more mature this time around.