Sakurai was saying that he wanted to avoid adding Japan-only fighters so as to not confuse everyone, but he also added he wasn't going to completely rule out the idea.
Marth was added, and Fire Emblem was *finally* ported to the West, and it was a raving success. Nazo no Murasamejo fits into a similar position; it's a series that needs to be revived, like Kid Icarus, has a ton of fans over in Japan, and would fit fantastically as a Western release. Nintendo is looking for a broader fanbase on the Wii. How kickass would a samurai game on the Wii be? And done by Nintendo, no less.
Yes, Takamaru is "old-school," but isn't Diddy Kong? He hasn't appeared in his own game for almost 8 years, and even that was a spin-off. He's been relegated to cameos in Mario Sports titles; not exactly "glorious." Yet, Diddy Kong is constantly requested by fans, because they remember him and they liked him, despite him not actually being in a game for such a long time. How about Samus. She hadn't been in a game for 5 years when the original Smash was released; Marth hadn't been in a game for 7.
Time doesn't matter. The character's are popular, they clearly stood the test of time, and, ****, PIT hasn't been in a game for FIFTEEN years and he still made it.
C'mon. Takamaru has a frigging shot at getting in this game.