Can't understand why people are not hyped for this game. It will be the first major game which will use the touchscreen of the Switch intensely. It was one of the biggest Wii U games with a large fanbase and even an official website for sharing levels (Mario Maker Bookmark). With the knowledge of part 1 we will have a well balanced online mode right from the beginning. It will be the first game on Switch which could use Facebook or Twitter as a replacement for Miiverse. Probably we can use Amiibos reasonable.
I made more than 40 levels on Wii U and had so much fun on creating levels. This is one of the games why I bough a Switch console. Already pre-ordered a copy with a stylus.
I think we will have another (Indie) Direct before E3 to cover titles which could come too short during E3. A Mario Maker Direct was necessary since we only know 90 seconds of this game from the February Direct and this is one of the biggest Nintendo games this year (beside Pokemon and Animal Crossing). On E3 they will focus on Pokemon Shield/Sword obviously.