In my opinion Dory is a deeply flawed character. I don't think she is a good role model at all for children, even if something might be learned from the movie.
This is not Dory's story. It's not even Nemo's story. It's Marlin's story. This is important, because Dory's function in the narrative exists precisely because she is a counterweight to Marlin.
The story is not pro-Dory. It is anti-old-Marlin, and it is using Dory's character as a foil to highlight Marlin's deep character flaws. That is not to say that Dory has no character flaws either, but the movie dedicates more time on the things Dory gets right and Marlin gets wrong, because it's about Marlin's arc and how he thinks he's right but is oblivious to his own mistakes.
Dory's memory problems mean she doesn't remember who Marlin is half the time, meaning she forgets the very serious purpose of their adventure, and she often leads them into dangerous situations.
And yet, despite of all her flaws, she balances Marlin's biggest character flaw: paralyzing fear. This isn't a matter of responsible versus reckless. This is a matter of optimism versus pessismism.
Marlin is a well-intentioned but emotionally damaged parent who is projecting his fears onto his child, to the point of stifling Nemo's personal growth. He is archetypically helicopter parenting and micromanaging Nemo, being too busy with his own worry about what might go wrong, that he absolutely dismisses the possibility that something might ever go right.
Dory, by herself, isn't a healthy middle ground either, but she is similarly extreme to Marlin, simply in the opposite direction. She always assumes a positive outcome, even in the face of many red flags that would suggest otherwise.
The vegetarian sharks are a great example of this. Everything about this situation suggests that it's deadly to go near them, but Dory doesn't acknowledge "common sense" and instead deals with what is in front of her. She doesn't judge the sharks unless they give her reason to.
As it turns out, she ends up making friends with a pair of sharks who very much deserve to not be ostracized by other fish, due to their principled desire to go against their very nature and not eat other fish. Marlin would've wrongly ostracized these sharks and would never have given them a chance, or even considered that they may not fit with Marlin's stereotypical views of a shark.
The minefield of jellyfish is another example, at least how they got out of it. Marlin was overcome with analysis paralysis because of his fear of dying or getting hurt. But this would've led to him never escaping.
Dory, on the other hand, while not fully acknowledging the mortal danger either, was able to take action and save the both of them (to Marlin's credit, he also took action after he saw her do it)
Marlin has lost all joy in his life. Dory represents and overabundance of joy and positivity. Neither of them is individually balanced. Marlin is unable to enjoy life or Nemo, Dory is incapable of assessing everyday risks. They need eachother to balance themselves.
If you want another movie analogy, Finding Nemo is like the movie Inside Out, if the protagonist had been Sadness instead of Joy. Rather than living with positivity and learning to accept sadness, which is Joy's story, Marlin's story is about living with sadness and learning to find joy.
If you're looking for a character who is not flawed (as shown by the movie), you have to consider Crush, the turtle:
He is kind, compassionate, patient, and is shown to have a really good idea on how to balance both keeping your children safe but not refusing to let them grow up or live their life. The movie explicitly shows Crush' children leading happy lives, in the same way that Nemo very much tried to in the beginning, only to have Marlin hold him back from his first day of school.
Marlin needed to learn to not hold everyone else back because of his own fears. This movie was a two step learning process for Marlin.
First, Dory taught him to be happy and playful as an individual. He was still an overconcerned parent, but due to Nemo not being around, Marlin eventually became playful with Dory (right after the jellyfish, if I remember correctly).
Secondly, Crush taught Marlin to be happy and playful as a parent. Parenting takes more work than managing your own emotional state, and it comes with some additional worries, but Marlin needed to learn to not hold Nemo (or himself) back because of him needing to be a parent.
In a way, Dory represents Nemo, but without the parental context which allows Marlin to claim authority. Instead, he has to treat Dory as an equal, which makes him incapable of not listening to her, which in turn forces him to understand an opinion that is not his own.
Marlin never heard Nemo's cry for joy, but he's unable to drown out Dory's infinite well of optimism and playfulness and eventually both acknowledges it and starts engaging with it.
Much like how Nemo has a simile in Dory, Marlin has a simile in Gill:
Similarly as my point before, Gill represents a non-fatherly Marlin, giving Nemo the chance to understand how emotional damage changes people, without the parental context of having to almost blindly obey Marlin as he is his father.
Gill's flaws are similar to Marlin, but they are more visible. He is physically scarred. He lives his life in service of the grudge that scarred him. He is most definitely not emotionally balanced, but he's also not a bad person. He's just broken and trying to get by.
However, contrary to Marlin, Gill never surrenders, even though his surroundings give him every indication that he should. Additionally, he elaborates on his (flawed) positions and reveals his reasoning, which allows Nemo to understand where he is coming from. Comparatively, Nemo never got to understand his father's emotional state because Marlin never acknowledged it himself or even let it be up for discussion.
However, I'm being slightly unfair here. Old Marlin did initially surrender, succumbing to his fears and living life the way he did. But he did not give up on finding Nemo. It's the one thing that incentivized him enough to reassess who he is as a person and who he needs to be in order to find Nemo again.
Dory acts as a guide on that path. Marlin needed her, but he needed to work with her, which forced him to allow her to be who she is. Which, by the magic of narrative analogies, is precisely the lesson he needed to learn about how he should parent Nemo.
In my opinion, this movie is a stellar example of how emotional damage can turn someone to act against their loved one's best interest, but for understandable and human reasons, not selfishness or pure evil.
To Nemo, in the opening scenes, Marlin was the villain. But the movie didn't paint Marlin as irredeemable. It actually revolved around disassembling Marlin's emotional state, and rewinding him back to a happier version of himself, and getting him to open up to the world again.
That doesn't take away that his wife was killed. It doesn't change Dory's life-altering affliction. It doesn't change Nemo's malformed flipper. And yet, he learns to life live inspite of the mishaps, as opposed to avoiding it.
That is the power of Dory's character, and how she should be valued.
