Its not great, but I'm willing to bet its 'updated'to allow this after release. Hopefully as a free patch. The backlash will be enough for them to look into it I would have thought
The problem with Nintendo is that they only seem to care about the Japanese market. There it is expected that you play online to play with random strangers but that you have no interest in communicating with them.
This results in random matchmaking taking priority with playing online with friends being an afterthought, as can be seen in Mario Kart's weird way of joining friends, Splatoon's lack of game modes for groups, and Smash not having matchmaking 2v2 unless you're on the same console as your friend.
Apparently there are very few complaints about Mario Maker's planned online mode on the Japanese twitter account compared to the US one.