Seems way too soon to release DLC. A lot of the kids that make up the Pokemon target audience have probably not played the game yet because they're going to get it as a Christmas present. Let them get it for Christmas, play for a few months, then time the DLC with when those kids are just starting to get bored with it but would be interested in new content to spice it back up. Now I suppose Nintendo might be thinking that the idea is for the DLC to be the Christmas present.
We know what this and the DK DLC are. They were released so soon after the game's release that you know they were at worst almost finished when the base game launched. A lot of DLC is just taking a chunk of the game out and charging extra for it. But Nintendo can be a little more clever about this and not make it so obvious. Have some patience and wait at least six months. "We made some more content for that game you love" is such a better sell than "We held back on this to make you pay extra for it."