Something always rubbed me the wrong way about Dixie as an echo fighter, but I always kept quite about it until now because I couldn't put my finger on why. Until now.
The reason I'm satisfied with characters like Dark Pit, Dark Samus and Lucina as echoes is because, even despite liking them and having ideas to declone them, none of them would have made it into the roster otherwise. Beggers can't be choosers and whatnot. Even in the case of Shadow I have a difficult time seeing him get in as a unique character before the even more iconic and recognizable Tails the Fox.
But Dixie Kong? I always felt like she had a chance. We're running out of must-have first party characters and she feels like one of the only ones left. Seeing a character who you never actually expected to get in can be exciting, but seeing character who had a strong chance of making it in as unique get relegated to an echo spot is slightly dissapointing. I feel like it'd be better to save her for DLC if they want to include her but can't without cloning.
That said, I could still see them adding her. It's not that she wouldn't make sense as an echo if they tweak her right, it's just that it wouldn't really sit well with me.