Smashboards

We weren't hyped to Ryu with "were getting someone from Street Fighter."
Not to mention, Street Fighter has had time to develop its roster.

If we got a Mortal Kombat character, it would be Scorpion.
If we got a Soul Calibre character, it would be Nightmare.
And when we get an ARMS character, I'm betting on Twintelle or Min Min, if not a selection of many which may include Spring Man.

I don't know anything about Soul Calibur, so I can't say anything about it, but Mortal Kombat never had a poster boy until they settled on Scorpion and, to a lesser extent, Sub Zero.
If FP6 is not Spring Man, it will break a consistent trend since Smash 64, that Smash has always gone with poster boys as the first playable character from a series.
Plus, I completely disagree that Spring Man wouldn't be hype. He'd single-handedly break every fan rule, even the Assist Trophy rule, which is about as hype as a first party character can get.

You're taking it out of context.

A poster child takes time to develop in a game based on character.
The literal Poster Children of Pokemon were Charizard, Venusaur, and Blastoise. It only became Pikachu when he became popular due to the manga, and then anime. Which Pokemon made it into Smash Bros first? Not the actual poster children- but the character that became the favorite.

Spring Man was only the actual poster child of the first game, because he is bland- because he communicates to parents, and people looking at the box art of a new IP, what the game is. The immediate blowout stars, the PIKACHU or ISABELLE, were Twintelle and Min Min.