Nah man, Estelle is basically the same character as Collette, with less face planting. I get that they tried to make her different, but they did not succeed. There's a lot of things about her that just feel completely unfinished. Like, they make it seem like there's some romantic interest between her and Flynn, or between her and Yuri. Unlike most other Tales games there is no system in place to explore either of those relationships, and it disappears completely less than halfway through the game and is never explored. What we're left with, is a character who is ignorant of the world, and needs things explained to her all the time. She's a lot less grating than Collette, but her role in the story, and social role in the group is pretty much identical. She's a moral compass, who doesn't know any better.
The "sheltered" description applies to Luke from Abyss as well, but if you play the game you'll find that even though he's not "stupid", just "ignorant", every single other character treats him like he's ******** the whole first half of the game. Then when they stop treating him like a dumb monkey, and give him some actual responsibility, you figure out that he actually is kinda stupid. He's a pretty irritating "main character", but not everyone can be as awesome as Yuri.