I don't think that people "complaining" are really so stone-heartedly dead set on these pictures rotting in the pit until a newcomer is announced.
The fact of the matter is, there's a new Smash Bros. game. Some of us get way more excited for it than others. I'll be the first to say, while I have a life, new games are always exciting to me, and Smash Bros is the absolute nostalgic pleasure center at the top of the pyramid. And the fact that Sakurai has made a development site ON HIS OWN ACCORD is a genius idea. But there comes a point when people start to get really hyped...and then they start to get restless. At that point, Gravitational Pull isn't necessarily the creme of the crop.
Again, that doesn't mean we need a character reveal every week until launch. But I'm sure there are more Assist Trophies than Skull Kid, Starfy, Nintendog, Ashley, and maybe Phantom Guardian. And there are probably more stages than characters, between both games, as are there more trophies than just Saria. Are stickers back? Is Ridley a stage hazard? What other stages are in the Adventure Mode other than Mystical Aztec Spinny Wheel and Magical Underground Cave Tree? There is just SO much that Sakurai could talk about.
I wouldn't call it being ungrateful. We just understand that this is Sakurai's willing marketing ploy and wish to see him put it to good use and allow it to serve it's purpose: getting people hyped for the game.
Was it a bad post? No. I just want something a little meatier.