I'd personally be more upset if Pikmin 3 wasn't released in August this year, but that's mostly because I've been waiting for that game much longer than I have been for the next Smash. Furthermore, it does seem like something Nintendo would do, they said Pikmin 3 would be released for the Wii, and it wasn't. Then they said it was expected to be a Wii U launch title or near it's release date, but they delayed it by several months.
Either way, depending on the amount of time they have spent on the game by the time they say they'll reveal a trailer, they may not have not done enough work on it for it to be shown. If it doesn't show much, I'm sure a lot of people will be disappointed, but would it be worse if there wasn't any trailer at all? if Nintendo has confirmed the trailer to be shown at E3 2013, then it should be, and if not, then that's their fault for not working on it early enough.