I don't think we should use pre-orders to indicate the success of Labo, which is an entirely different product compared to the usual games we know. It's not something most young adults would buy, and I would assume that particular demographic are the ones who mostly pre-order games, its targeted audience are children and children at heart.
Labo has been marketed as such, through various hands-on events that mostly allowed adults with children.
As for what it can ultimately do, we don't know. If the PS3 could create a supercomputer in the Air Force and the Wii could get seniors to play video games, I'm sure Labo will find it niche somewhere, especially when you have seen some of its potential through Nintendo's videos.
As for those who don't care or want this to fail, guess what? It's not for you and that's ok. Nintendo thought this would be a nice way to not only expand the demographic of the Switch, which is predominantly young adults, but also showcase the potential of the Joy-cons, which have had their moments in various games such as 1-2 Switch, ARMS, Doom, Splatoon 2, etc. Nintendo has a mind of a toy maker, its been in their DNA for decades. Heck, this is possibly inspired by their previous toys back in the 1970s.
We'll just see how Labo hangs around in the market.