You are making those arguments based on the assumption that the Smash team wouldn't want to fully develop Dixie as a new character.
The game already released and all the DLC characters are going to be original. We have long passed the phase of speculating for echoes or semi-clones (And items BTW, they won't add those as DLC ever. Otherwise multiple issues for online FFA would arise).
Think outside of the echo box. Dixie's ponytail can't only be used for helicopter twirl and only that. It can be used for multiple disjoint attacks (That
can't do), those disjoint ponytail attacks could be all the aerials, some tilts, and of course, Smash attacks. All that while Dixie's hands are free, unlike a weapon wielder. There aren't many characters with this qualities in the roster (I can think of only
,
and
, and they don't use their tails/Kazooies in many moves even).
The ponytail being used to grab barrels just like
in DKC2 and 3 could be brought to Smash in multiple ways, a cargo grab, a command grab, a normal
-like grab and so on....
Tropical Freeze added a new move for the ponytail, so that means she can have a recovery that is very different from
's and use the classic helicopter twirl as a
's float-esque move. Also Tropical Freeze gave her a projectile with different properties from
's peanut gun, which (Like many of his moves) came from DK64, a game Dixie wasn't part of. Finally, Dixie is also slower and less acrobatic than
.
Smash can take a deeper look at things that weren't relevant or didn't exist in the original games and give them a new utility. There you have
's belly, that wasn't relevant in his appearances outside of looking shiny (I know if you try to roll it in the DKC games, a visual red clank appears, but every single boss in the series is immune to rolls anyway). And
using that belly armor in Smash doesn't make him "not of the DKC world".
If you don't see a completely original fighter there, then I don't know.... assuming that a fighter can't be original just because it "might" be an echo it's just wasting a good moveset and losing the character's identity in the transition. If Dixie is perfectly translated to Smash then DK doesn't need more representation ever again. Heck, I would even be happy if they bring her in with Kiddy as a tag team (Now excuse me, I have to reach the bunker before the Kiddy haters ask for my head).