This information comes from Nintendo of America president Reggie Fils-Aime…

“You know, for us, we believe that having hands-on opportunity married to an announcement is really the best way to do it. And so let’s take Super Mario Odyssey for example. We could have announced it months ago, but we weren’t yet ready, the team wasn’t ready, to show it and to let the consumer really understand visually how the hat mechanic works, how the capture mechanic comes into play. And so that’s how we think these through.”

“For certain games, games that will be in development for, let’s call it a decent amount of time, like Metroid Prime 4 — also, given that it’s a franchise that we know people have been very eager to get some news — that’s when, fine, we’ll share it. We’ll share it early. Others, we want to hold closer in and reveal it when the gameplay is going to be available. It literally is game by game, title by title, how we make that decision.”