To put my thoughts in a nutshell, I think Nintendo is doing alright by the few seconds of footage we seen. We shouldn't expect Wii U visuals from the 3DS, and to "get it out the door" they turned the games from the 3D puzzle platformer, to a 2D puzzle platformer which will put less stress on the system, and developers to make a great game. It is easier to make a well thought out puzzle in a 2D space then a 3D one.

The art is definitely lackluster, which also makes the game look even worse.

But when you are doing a spin off the term "proper" is pretty relative, a spin off is supossed to be a different take on the franchise.

Also, about your despcription of the game on the op, is kind of funny, but that sounds exactly as how someone would define Kirby Mass Attack by watching a minute of gameplay, go from left to right tapping the screen to throw kirby clones, what a shitty game right? Except it wasn't, people liked it and it was mostly praised (83 on meta), I really liked it too, this game seems to have a very similar concept of gameplay, so yes, it could work, the only thing that has me worried is the studio behind.

Even as a spinoff though, it just looks quite low quality. And even for series spinoffs, people have certain expectations. For example, if I go to a restaurant and order a pizza, and they give me a pancake instead, I'm not gonna be overly thrilled.

I also think it looks bad, and the whole spinoff after spinoff after spinoff thing is getting old.

I even made a video about it. Got tons of hate for it. Still coming in, actually.

Do you think Kirby Mass Attack was a low quality game too? Because I have to insist, this is following the same style of gameplay, you are being quite superficial in your judgement here and you couldn't possibly have any expectations about an unexpected spin off, you didn't order that pizza, there is a pancake on the menu and you complain cause you want Pizza intead, that doesn't mean the pancake is bad (God I hate metaphors sometimes).

At this point, do we really expect Nintendo to make constant new mainline games for these systems besides BotW and Sun and Moon? Not really. 3DS can still sell but they've pretty much put out whatever big game they could put out with Sun and Moon probably being the last of those big games. Wii U is not getting better in terms of sales and with NX around the corner, not much more they can do besides spinoffs and smaller titles or titles with re-used assets.

Basically, if it isn't a pizza, don't call it a pizza. Don't slap a franchise name on something unless you're going to deliver on what makes that franchise great. 

And I can't comment on Mass Attack, I'm not familiar with it.

Mass Attack was also a pancake, it turned up to be better than many "mainline" games of the franchise.

Having looked into Mass Attack, it at least looks like it delivers the cute charm, problem solving, and creativity of the franchise.