And the truth people have to realize is that Geno really isn't all that important anymore. Yes, he was in a game that's considered a classic, but he ended up in a really bad situation between Nintendo and Square Enix, and ended up on the Square Enix side. Thus the only thing he's gotten in 20 years is a cameo. There are other Mario series which have delved into the RPG genre anyways, and have done so more successfully and have become more famous than what's now an old title.
One thing to take into consideration is that Geno is considered a 3rd party character, and if Sakurai really wants another Mario rep, it's just so much more easy to go for Bowser Jr, or heck even Waluigi, and still get a good response from fans. Right now those two characters have bigger support than Geno anyways, it'd be a win/win situation for Sakurai to just choose either of those two, he'd avoid getting into a heated argument with Square Enix, and he'd get a better fan response. They're still appearing in their games, and they're more recognizable. I had never seen Geno before people suggested him for Brawl, unless you're a big Smash Bros fan or happened to play Super Mario RPG back in the days, you won't know who Geno is. It's always best to go for the more recognizable faces
As I said previously, I'd love for Geno to get in more than the other possible Mario reps, but a miracle has to happen before he'd make it in.