Pal, I love the Metroid series and enjoy playing ZSS and Samus in Smash. I'm not obsessing over a physical attribute of her.
Like I miss TP Zelda and Ganondorf, but those designs aren't being used anymore, and that's that. Same way I love using fat Pikachu, and it's never going back to that.
If you like the character so much, you shouldn't be hung up over one single thing.
You should be happy that she's still there.
She still has the same breast size, it just she doesn't have boob socks like she did in Brawl and Smash 4. Like everyone else in this thread has been saying:
Drop it and get over it.
I mean the actual thing I'm curious about if they get into Smash, is if they're going to translate them over to the style of Xenoblade 1 and X or stay like their home incarnation.
I think it'd be a little odd to see a different art style between two characters within the same series, not like it can't happen though.