I feel like some of the criticism leveled at this game is more about wanting all Kirby games to follow a strict forumula, what with all this continued talk about "traditional" Kirby gameplay. How many people dislike this game because it's not that well made of a game, and how many people dislike it because it's not more of the same "traditional" gameplay?
Just about half of Kirby games are the spinoffs, so if people are saying non-traditional Kirby automatically is a bad thing, then they're wrong. Assuming "traditional" refers to sidescrolling, inhale+copying Kirby, then we haven't had many good new games in that department either, arguably since Kirby 64. The last new traditional Kirby was Squeak Squad, which just wasn't very good.
I'd like to believe the last good Kirby game we've had that's not a remake was Canvas Curse. That's a spinoff sir.
As far as my experiences go, his non-traditionals are generally better if they use copy abilities. The ones that don't are Pinball Land (though he is technically using Ball ability), Tilt'nTumble (not even using Ball), Star Stacker & Super Star Stacker, Avalanche, Epic Yarn, and Mass Attack. Star Stacker and Pinball are probably the only two I really enjoyed of these, the latter probably because it was the first Kirby spinoff.
That matter is a bit off-topic so if this seems to warrant discussion, you should make a new topic.
As for Mass Attack's handling of it, I'm not a fan of them making the game almost entirely unfamiliar from Kirbyverse, much like Epic Yarn did, though Epic Yarn was because it wasn't a Kirby game until the last few months of development.
There's very few old enemies, while lots of the new enemies in this game could have someone else from past games that can do basically the same thing. Part of what I love about Kirby is taking on familiar enemies in different ways. I wanted to see how you could fight a Bonkers or Mr. Frosty or someone we know in this style. Copy Abilities would help reinforce that and add to its replay value, though it's not absolutely necessary.