Metroid has an identity and the pillars are well established. Much in the same way that almost the entirety of the 3D Zelda series has just been remaking Ocarina of Time, so too has Metroid basically been remaking Super (or, by extension, the original). And that's fine, because the implications of "remaking" are mostly facetious, and more just a means of identifying a moment where the franchise found its identity. Games can, and often do, find ways to rejuvenate themselves while still keeping their core identity. Originality comes from reimagining not the franchise, but the intricacies of the pieces that make it up. In Zelda, for the longest time, it was the items and how we used them. In Metroid it's largely the same.
Not that I'm suggesting Metroid also couldn't have some major moment, like Breath of the Wild, where the series is turned upside down a bit but still retains the essence of its identity. But it's a difficult line to tread, because just as easily can it feel refreshed as it can eroded and rebuilt into something entirely different. And at that point, why bother? It's just a new game with an old franchise attached to it.
Metroid when it's not overly cartoony, and a bit grimier, is my preference not just because of aesthetic and tone but also because it diversifies Nintendo's line-up. I've said it before, but Nintendo's software identity is distinctly Japanese for most part, and Western influence helps diversify. It's exactly what Rare, Silicon Knights (if briefly) contributed in the past, and what Retro and Next Level contribute today. Metroid, despite obviously being Japanese in origin, has largely transformed into something distinctly Western in design sensibilities, and I think it's important it stays this way (to Nintendo's credit though, it's by far their most "Western" series even when they develop it internally).
I'm probably over protective of Metroid, but only because of Nintendo's souring on the series for awhile, and my firm belief in not eroding franchises to replace them with something completely different yet act like fans should be happy. It's like when Miyamoto, I think it was, was quizzed on why we haven't seen a new F-Zero, and his argument was that they would return to it when they had an original idea to make it fresh. Which is fine, except this is around the time Mario Kart 8 had dropped or been announced and they'd shoe-horned anti-gravity into it. And the same company continues to peddle side scrolling Mario games that we all love yet are frequently just the same game we've always been playing with, now, multiplayer bolted on.
Anyway, one of 2020's ported Wii U game should be The Wonderful 101, but it won't be, because Nintendo cruelly sees no interest in it. Dogs.