Dawn went through some change character wise,but i suppose reason why some people arent satisfied is because they expected some drastic change in character personality being to them by end of run still that girly,confident and cheerful girl they used to know with all that struggles and bad times she went through being overlooked in their eyes.
Compared to start of Sinnoh its noticeable how she grew from overconfident character to more humble and down to earth person not being anymore so rash,full of hrself growing to realize how her approach toward contests an attitude was wrong bringing her loses and failures.After that she went trough depressing state learning on mistakes and growing in stronger coordinator gaining more faith in her skills when she started winning and when she finally proved to Johanna her worth.
Reason i liked Dawn was because of great interactions she had with Ash,Zoey,Ursula or Kenny being good character.Because of interesting story and development she went through gaining tremendous growth as coordinator with culmination of hard work being achieved position of runner up in Sinnoh GF.And because of all that burden and pressure she had from mother,her rivals and friends she carried on back having to prove her worth as coordinator and fulfill other expectations making me root and care for journey and progress she made.
She wasnt my favorite pokemon female with Misty and May being more intriguing,deep and unique imo.however Dawn was definitely one of better characters we had in pokemon so far.
I dont think those two are good examples to use,when trying to prove your point about Dawn.Anyone who watched original and Hoenn series can clearly notice how both of them went through notable growth.May developed a lot changing from insecure and clueless,ditzy girl to independant and confident character which learned to like pokemon,making name for herself as coordinator and deciding what to do with life.And finally let me repeat what I've said already: Misty got almost zero development and May...well, let's say she had learned how to deal with Pokemon by the end of her time with the group.
So, given these facts, I still find it kind of unfair that, while ignoring Misty and May, you're criticizing only Dawn although she was clearly the best and most elaborate of Ash's female companions.
While Misty went from short tempered girl which exploded over anything to more mature and levelheaded character toning down on violence along with getting over complex of inferiority caused by sisters becoming more responsible and confident along with making big step forward as trainer compared to early days.
In comparison i feel Dawn developed more story wise compared to both,but when it comes to character growth i feel she didnt changed as much as them.Even though you disagree,i respect your view on it.