It was a bad idea, but now it's gone.
Nintendo had previously planned to drip-feed its items (that you use to build levels) over a nine day period. God knows why.
But thanks to a patch it looks like that's gone.
Now it seems like the items are updated and being added every 15 minutes as opposed to every 24 hours. According to the patch info:
— “Create a course” scene: a small element was added. — Condition(s) for increasing the amount of useable parts (in the level editor) were added. — Various changes meant to improve the gameplay experience.
This could be a response to pressure, could have always been part of the plan, either way it's a far more elegant solution. I totally understand Nintendo wanting to drip feed items: it's about easing players into the Mario Maker experience.
But there are super users out there. There will be people making masterpieces within the hour and it makes sense to give those players access to all aspects of the game as soon as possible.
A good little compromise.