Those trophy items don't mean much at all.
They mean as much as enemies in Smash Run, Assist Trophies, and Stage Hazards. They effect the gameplay in some way, which is probably why they wouldn't be playable because they change how the game plays. I guess Excitebike Racer could pull it off with a unique name and design, but I doubt it.
They could easily just remove Excitebiker from the Assist Trophies, or make them discernible enough. Also, Villager and Mii were also dismissed publicly by Sakurai as not fitting in with a fighting game, while Little Mac was dismissed for being "unable to fight" (in Smash Bros.), and look what happened. I think that there is always potential for Bubbles and Balloon Fighter (both of which he stated would be unable to fight at the same time) because he has changed his mind while dismissing characters in a similar way before.
Villager was dismissed because he was "too peaceful", Miis were dismissed because the developers felt people seeing themselves being beaten up by their favorite Nintendo icons was probably a bad idea at the time. The inclusion of Miis in games like Wii Party and Mario Kart (where some sort of danger was actually present) made the idea seem safer. Bubbles was said to be unable to actually
fight. I thought Balloon Fighter was dismissed because they thought he'd be useless without his balloons. But he's still capable of fighting.
However, if he doesn't, Sakurai will have to end up looking for slightly less iconic retro characters, else not include retros at all. Furthermore, Muddy Mole as a franchise could do with a reboot. I'd never heard of Pit (or Kid Icarus) before Brawl, so there's always the chance that even though Muddy Mole is a little more obscure, his franchise may just end up finding new life.
I do not oppose the inclusion of lesser known classic Nintendo characters, I want to see Lip, Muddy, Mach Rider, Sukapon, etc. return one day too, I just do not see it happening for paid downloadable content.
Good point, AEM! Say, if you don't mind my asking, where did you get that adorable Nikki icon in your sig, and also, where's the awesome design of Excitebiker from?
You mean the one in the top row? I ripped it from the Wii U version: made a Mii Fighter, picked a pose I liked, took a screenshot, plugged my SD card into a computer, put it in photoshop and whabam.
Excitebike Racer is also from the Wii U version, but it's of his trophy. Though I had to do that through Miiverse. I did the same for Lucas, K. Rool, the Ice Climbers, and Dillon too.