This is the reason why I have such a huge problem with people judging games based on what they aren't instead of what they [italic]are[/italic].
There are many elements that fans have decided are what Metroid is, based on some actual elements that appeared in other (but not all) Metrois games. Things like (non) linearity, oppressive alien environments and identifying with your lone space hunter are characteristics that have been so heavily ingrained as what the series is by some fan. But at it's core the series is not about that, these are just individual elements that comprised some games or personal emotional connection that became pop culture representation. The series mantra is to be an action adventure game in which it is possible to continue to transverse the environment by acquiring power ups. Developers always condense what the series is to the smallest amount of characteristics possible not to betray fans, but to surprise them and themselves in the creation of a new fresh sequel. As Neff said, this is the difference between actual creative process and focus tested industrialized design.
Traversing and non linearity aren't the same the same thing and non linearity isn't a trait that must be present in a Metroid game by definition. Non linearity, veiled linearity or straight linearity should never be used as an evaluation or criticism, the merit comes in how a specific games design the map, objectives and flow of the game. Take Other M for example, most corridors in the game were small puzzle rooms in which you had to use problem solving skills with environmental cues in order to keep advancing. Cracked glasses, air shafts, or hidden switches are used to engage the player in different activities in order to progress.
If we only used the core "acquire power ups to proceed" theme, every Metroid game fits, and should be judged by it's own merits instead of arbitrary rules of what it doesn't do. Fusion is the perfect example, it's first and foremost a cinematic game experience, which is incorporated both narratively with the help of exposition and "in game" with the clever use of brilliant set pieces and with an adaptative environment, which changes as you progress the game. The Metroid principle is still in tact, power ups are used to progress and solve puzzles, hidden routes and mapping are prevalent along with action elements to spice everything up. While Super Metroid's way of naturally guiding you through the environment is master class in design and one of the key reasons why it is a masterpiece, Fusion's deliberate and outspoken design helps characterization (of characters and environment) and allows for a more rigid rhythm for traversing, which is important for not just new players, but everybody in how we end up actually playing the game, it defines it's tempo in order to guide you through the several set pieces. There's this pervasive way of thinking that games, because they allow freedom should be designed as an open playground, in which the player, through his agency, needs to run around freely exploring. This is not the best nor the only way of creating game experiences. Linear game design allows for many other interesting things, and of course should never be expressed as a complete dichotomy, as they can be employed through different levels.
Of course I understand that at the end of the day, subjective tastes are what you judge a game, and one might not like a game specifically because you don't like those elements, but it's important to make the distinction because it doesn't make the game bad. As for Other M specifically, it's a flawed game, has a few problems in implementation and vestigial ideas along with a bad localization (in which Mr Sakamoto was over involved in my opinion). I do not know if the collaborative process dynamics were, but I'm not too convinced it was smooth integration of ideas. However, it was a very enjoyable game that really needed a sequel.
Gonna make a little addendum regarding controls. I've had a few discussions where I realized that dpad controls could be cumbersome for some because of how uncomfortable the dpad itself is physically, it being a problem in 2d games as well. The in game implementation was great because of a very smart Camara system integrated with mainly a 4 directional movement. They made it so it plays like a 2d game in a 3d environment, where the Camara pans and rotates to your movement while having "rails" that course corrected the direction to the relevant point of interest in the room.
Combat is also widely undermined. It is designed to be simple, just like other games in the series, but there's skill involved in the strategies to correctly and swiftly dispatching an enemy. If you are just dodging and shooting charge shots then it's like playing DMC by just using 3 x triangle combo, it's gonna be slow and tiring. Normal rapid fire shots at the foremost, which become an interesting mechanic in of itself when you're desperately trying to get one more shot in before having to charge and dodge the attack. Missiles in order to interrupt and stagger enemies, which work great due to the slow time mechanic (I realize this is also controversial because of the untraditional input from the player, necessitating coordination. I think it's great and works like a charm but if a sizeable amount of people couldn't get a hang of it then it is sadly bad implementation). Knowing when to fire a missile can get you a lethal attack really early. Knowing what benefits and vulnerabilities associated with freezing limbs or why is it important to do jumping attacks really speeds things up. It's not a combat focused game, so not using all the tools isn't gonna mean death, just halt all your momentum (and other M is a very strong momentum based game). Charge shots have the worst DPS output in the game and should be avoided for most enemies, sadly most people only ever used those. Combat is about keeping things brisk so you can keep going.
Having Wii remote only controls is a design philosophy, in which in limitations begets creativity. Everything is built around it and it was a fantastic implementation and one of the reasons why I think the game is so cool. I do however think there's a disconnect between simple intuitive and inviting control scheme and the complex over stimulating action that appears on screen. That was exactly what they were going for but that's an audience mismatch. People are gonna be either to intimidated by the visuals or will be bored by the simplicity.
