Ordinarily I would be inclined to agree with you except for the fact that there are about 10 metroid games. One can only do isolation for SO long. At a certain point a) it becomes absurd that Samus has no interactions with other people and b) it becomes hard to interest anyone in playing again.
It's not absurd, even the early games make it clear that Samus has social interactions with others. Those interactions just don't take place in the game. Also, I don't think that it's hard to keep interest, not necessarily. If Nintendo can pull it off well, that's great! But the series has had two games now where a fair bit of the story involves people other than Samus and in both cases, the story is pretty weak. It's just not why I love those games. But if Nintendo wants to place us in the center of the Metroid universe, then that's what they'll do. I'll still play it, but the idea of a central, traditionally-told story isn't what will get me excited.
Personally, I feel like Metroidvania games are inherently broken. There is a tiny window where they are functional games, and a ton of fun, but then your character becomes over-powered and you fly through all the levels in a manner completely removed from how the game is actually played. THat "feels powerful", but it's not great gameplay to me. having multiple worlds could help mitigate that, to some extent.
So why on Earth are you even playing these games? Part of the challenge is in using your new abilities to find secrets. Hey, remember that little morph ball hole you saw that was a few blocks off the ground? Notice how bombs now make your little ball hop a little? Cool! Go back there and use those bombs and the morph ball to jump in there! That's an easy example, of course, but the challenge and fun isn't necessarily found in difficult enemies and you don't necessarily "feel powerful" because you can now kill those early-game bugs in one shot instead of four. Have you ever finished Super Metroid? Think about how you feel in the last ten percent of that game. No part of the environment that is destructible can stop you. You can jump infinitely into the air and your mid-air somersault itself can kill anything! You can run so fast that you burst through everything! Hell, you can even swim in (most) lava like it's an indoor swimming pool on a cool day! Some pools of lava - might be acid - can hurt you, but otherwise every bit of that world is open to you, you'll never turn away from another item again because lack the ability to get it. That's where the satisfaction comes from.
Placing the game on a single world enhances the whole discovery aspect by having areas link together in unexpected ways. When you have three or four different worlds, that obviously can't happen, unless they have you travel between worlds with portals or something.
I think I should be more clear because apparently I'm not communicating properly. I've been playing Metroid since the original and, yes, I've beaten every single one. Being that I am the age that I am, I don't believe that "story" necessarily means movie cut scenes and voice records.
When I said that the game should have 3 different worlds, that is why I said that the game should have a hub world. Old school as I am, I think games function best when there is an overworld that allows the player to choose what they want to do. It think every game should have at least 3 fronts that the player can be working on at any time. Take Doom, for instance, where a player can play a new level for successful completion, and old level to 100% secrets or an old level to 100% par time. Or Super Mario World where a player can play a new level on the main route, play an old level to find an alternate route, or play Star Road. The best adventure games like Day of The Tentacle and King's Quest 6 were also good at allowing the player to progress on multiple fronts if they so chose.
I think giving Samus a Space Bar to act as a hub world would give the player the opportunity to not get "stuck" which would make the game MORE accessible and allow the developers more room to make the game more difficult, which is something that is important to a player like myself. Can't beat Kraid? Fine. Go do something else for a while and come back when you are in the mood to try again, or have more energy tanks.
You mean like giving the player quests or something? If they're going to put Samus in a more social environment, that could work pretty well. I'd still like to avoid objective markers, or maybe just not give every quest an objective marker (if someone wants you to, say, go kill a monster and they know where it hides, that would be all right). That's skirting pretty close to an RPG. Dust: An Elysian Tail actually did that pretty well from what I remember.
Also, I don't think I mentioned this before, but if they are going to put Samus in a more social environment, I'd rather have her voiced when people speak directly to her. I'm tired of silent protagonists.
Sorry about misunderstanding what you meant by "different worlds".