I can definitely see where you're coming from this angle. In regards to Esmeralda, I think it's a combination of being in a film that didn't do well successfully (or successfully for Disney), Disney treating her not unlike Kida (another POC heroine) --- a throwaway --- and being a woman of color character. She's quite unlike the previous heroines of the Disney canon, I don't even think you could compare her to someone like Megra and for that she is in a league of her own here. I do think that if she was characterized and even modeled after the popular Ariel or Rapunzel or was white, she may have been better accepted by a larger audience. As it stands, I do think she has a strong following --- especially among young girls of color (I vaguely remember seeing a lot of girls with Esmeralda merchandise as a kid), but said following is typically overpowered by the larger Disney Girl fandoms (Ariel, Jasmine, Rapunzel, Cinderella, Snow White, Belle and Aurora) and forgotten like so many female characters who aren't under the "Disney Princess" label and that's a truly disappointing fact.