I think it probably hasn't reached 1 million yet. Judging by Japan performance it probably sits somewhere around 600 - 700k right now, which is decent but not a runaway hit like Splatoon or Mario Kart was.
If I remember correctly Mario Kart reached it's 1.2 million on it's first weekend in about two days and Splatoon was a special case because while it had an amazing launch for a new IP it has even more amazing word of mouth and legs. These games sold/sell extraordinarily well, Super Mario Maker probably sold only good so far.

probably they're waiting for a different Milestone that has to do with the Mario franchise. Let's say, maybe they've seen the game sold like 1M FW so they decided to wait until it reaches 3M since it's Mario's 30th anniversary (?) I know it's kinda dumb but hey, it wouldn't be the first time Nintendo makes dumb decisions, the game has for shure sold over 1M alredy imho

We have to wonder whether Nintendo depleted their marketing budget on Splatoon or they spent just as much on SMM.

I don't think this game has a big an appeal as a new Mario game. Some people prefer playing games instead of making / redesigning levels and for many of them, this still isn't as creative or as open as LBP.

It probably doesn't help that Nintendo has strict YouTube policies as with LBP a lot of the other sales came through the amazing videos being uploaded and shared.

If it hasn't already, I think it will sell a million and probably go on to do 2mil by the end of the year, it's Mario after all.

Because its selling less than expected... Most likely.

Because they waiting for some milestone.

They revealed Splatoon numbers after around 4 weeks.

Maybe they are too busy right now.

As many have said probably hasn't reached a notable milestone yet (a million would be the one). I wouldn't worry too much right now though. I would start getting curious however if we don't hear anything by next NPD though.

Maybe this is one of the few Nitnendo games that will drop in price. As hyped as it has been and it being a Mario title, it had to receive an excess print run. Maybe I'll be able to pick it up for $30 or less one day. I think it's way overpriced for what it is, but $30 is reasonable.

Definitely overpriced for how lacking in options it is. I think the real mario maker will appear on the nx, don't think they wasted too much time on it as a wii u game at this point