Good question about Carrot and Yamato, actually.
The only thing I didn't like about Carrot were people aggressively pushing her to be a SH. Great Wonderland references in WCI, amazing Sulong, overall fun as a supporting character. The conclusion might've been better, tbh, but that's it. Carrot is a bit like Perona to me in this regard - interesting character, important in her arc, great now let's move on. At least she's consistent in her characterisation.
Yamato, on the other hand, turned out to be such a mess :( on the good side, the introduction was great (but I would hold off the gender reveal) and there were also so many promising moments about this character, the will to break free after 20 years of prison, connections to Kaido & Ace, sheer strength & cool fighting style, interesting DF (I'm a sucker for wolf-themed characters), oni race, being a tomboy, I could easily picture Yamato as a part of the crew and it would've been fun. On the bad side, absolutely hate Oden wank, and knowing Oda it would annoy me to hell same as Sanji's nosebleeds (and Sanji is my fav SH). Also absolutely hated inconsistency in Yamato's character, "yep I will guard Momo and will die for him" "oh no sorry I wanna fight Kaido, so I'll be off" - boom, Kaido happens to be in the same room as Momo and Yamato is not there D: and don't even start me on "I wanna leave! I will sail with Luffy!" vs "you know what meh it was just a phase". So I feel like I was deceived by Oda, and even if now Yamato somehow does join the crew before the series end, it's not going to be satisfying in the slightest.
Lol, I feel like I've triggered myself, obv I'm still salty af, but you kno what? Now that I'm not actively rooting for any of the characters, I quite enjoy the story and am hyped for the Egghead arc.