This right here. The death blow would have been softened so much more if Shadow and Knuckles had been revealed in reverse order. It really doesn't make sense why they'd save the last Brawl AT from Smash 4 (as in, debuted in Brawl and reappeared in Smash 4) for the final Direct alongside many new ATs. I have to think he either was developed late or they seriously thought people would be excited over his "return".They couldn't have thought that seeing them add an emerald would be that exciting of a reveal. I actually think it would have made more sense if Knuckles was the late reveal and they showed the updated Shadow first.
Frankly at this point I wouldn't be surprised (in fact I'd be amused) if we get a Shadow Mii costume this year in response to all the hype he generated.