That's reaching too far for Dixie-fans to settle on for asking her to be a semi-clone - since there's a clear backlash already on her being an Echo.
Just because it'd be easy way to please the crowd, doesn't mean it's the best one to go with - nor Dixie-fans should be "grateful" for Sakurai about that, if that's all he'd make her to be. If he sees her as an afterthought, so will Dixie-fans, because they're essentially receiving Girl Diddy instead.
It's all depending on how Sakurai sees Dixie as, anyway. But since she was considered to Brawl as Diddy's tag partner, it shows some hypothetical proof that she'd been looked on more depth than just being Nana to Diddy.
Along with this is the constant emphasis on her trophies talking about her ponytail centrally, showing that Smash-series isn't ignorant on her unique traits that distinguish her from Diddy at large. You could see this even in her Smash Tour Trophy-function, which allowed the player to gain an extra jump - referencing her special skill in Tropical Freeze. This kind of shows that Sakurai and his team aren't ignorant on Dixie sporting unique abilities.
The current assumption now is that Sakurai will be adding Dixie as an Echo due how Diddy might be having a tail-less jab compared to last game, and (strangely) well-received and easy way it has become in the fanbase, as well as having done already less accurate additions in the past before (Dorf + other Echoes).
Now the question is, will Sakurai go being completely ignorant on how he considered Dixie before because how Echoes seem so easy to implement, in exchange of their unique traits. At the moment, Dixie being considered to Brawl seems to bit of rally against that, along with how she's been portrayed through trophies up to this point.
This all before all the arguments indeed on why she shouldn't be an Echo, due how it'd go completely against her uniqueness up to this point, and probably taint it for good as so, because people will start thinking or even claiming she was "Girl Diddy" all along, much like what happened to other Echoes.