Well, you just name a character that exactly has a significant role with in a single story, so thanx for that.
My point wasn't meant to despise Geno and hist situation. I play SMRPG and do recgonize how he and Mallow participates in their stories, but the main point is that Geno isn't the only character that pays efforts to compete a story, but other Mario characters from different stories did that as well, so did the characters of other Nintendo games. If you use recognition as the only reason why Geno can be promoted, that may be applied to many other Mario characters in the first place.
Like said in previous replies, Geno is named due to his great popularity, likeability and potential more than his recognition, so we're not really suppoed to discuss about the latter. The only pratical way for him to gain more recognition than other characters, is to participate in other stories outside SMRPG. That is essentially what Rosalina is doing after Galaxy.
I remember some of the core fans want a direct sequel of SMRPG, but like said, since each Mario RPG is likely an enclosed story, even if we got SMRPG2 right after SMRPG, it feels like there's a great chance Geno would be replaced by new party members like how Paper Mario TTYD. So the more reliable way to keep him in spotlights is a different type of game.
Luma is a species but seems like there's one pearl-colored recurring Luma along with Rosalina. With that said, that reminds me of Twink and the seven star spirits from first Paper game, and the spirits actually prove that RPG characters may appear outside their original game. So it's sad that we don't see that happen more nowadays.
Aside from other original characters, my main critique is that Nintendo could had make use of existed species and give them alternative skins to make the party members real inclusion. It feels like making a Lakilester skin as an alternative for a generic lakister isn't really that hard work.