Everyone knows we are long past the days of the mascot platformer being the standard bearer for a platform. Sonic, Crash, and Mario had their day in the sun, but these days Crash is a minor character who is platform agnostic, Sonic games are few and far between, and while Mario is still one of the top characters in the world, platforming is a relatively small part of his game portfolio.
That doesn't mean that game characters don't matter anymore, though. Nintendo's whole market position is built around characters, from Mario and Link to Samus and the Animal Crossing crew. Their biggest IPs are built around characters, and virtually all of their games star some recognizable frontman/woman/creature.
Sony's portfolio of games may be more mature oriented, but it is also largely character driven. The Uncharted series leveraged people's love for Nathan Drake and his friends to soar to new heights. The Spider-Man games are a fresh spin on one of the most popular characters out there. Ratchet & Clank. Sackboy. The Astro games. God of War. Horizon Zero Dawn. Sony does have some franchises that aren't particularly character driven (like Gran Turismo and Demon's Souls) but much of Sony's IP is focused around strong and recognizable characters.
Then we get to Microsoft. Their most famous franchise is arguably still Halo, and from that Master Chief has become a kind of unofficial mascot for the system, but he's almost a non-character in many ways. Over the course of the games he's built a personality and backstory, but they've never taken center stage, and the fact that you play Halo from the first person perspective means that he fades much more into the background of those games than Nintendo or Sony's characters tend to. Halo is also at least in part a multiplayer driven series where Master Chief isn't even involved, with players instead taking on the role of nameless Spartans.
There's also Gears of War and Marcus Fenix, but he's rarely trotted out as a representative of Xbox these days, and he's even been de-emphasized in his own series, which is more multiplayer focused. Microsoft's other big franchises don't tend to have any consistent characters at all. The Forza games obviously don't. Minecraft has Steve, but again it's first person and Steve is a non-character. The Fable games started you fresh each time, free to built your own avatar and spec him how you liked. In Crackdown you make your own agent. Killer Instinct has characters but Microsoft has never pushed them as brand representatives. The Ori series is well regarded, but I never see anyone talking about Ori itself.
Even the studios Microsoft bought don't tend to create persistent characters from one game to another. Bethesda games are famous for making you create your own character from a variety of choices. Obsidian games do that too. B.J. Blaskowitz and The Doom Slayer are iconic characters in their own way, but in the context of their franchises rather than any particular platform. Doublefine does create memorable characters, but they also make more niche, smaller, games that don't make for good standard bearers.
Microsoft tried to make characters in the early days of its console business, churning out platformers and fighting games that nobody really cared about, which is why Master Chief ended up as the mascot despite Microsoft's best effort to make Blinx or Voodoo Vince or Tao Feng happen. Since then it seems to have given up. Obviously it hasn't stopped Microsoft from having success in the video game business, but I do think that there are advantages to having characters that people care about. Nintendo leverages Mario and Pokemon to push people into all kinds of games they might not otherwise be interested in. How many people bought Pokemon Snap because it was a Pokemon game rather than because they wanted a photography rail shooter? Sony uses its characters to keep people loyal to their platform, because you need a PlayStation if you want to see the continued adventures of Kratos or play the latest Spider-Man title. Characters give a platform an instantly recognizable face and emotional investment in games and a platform. They make people forgive flawed games and wait through release droughts because they are fans of a specific thing, and that's a thing they can only get from that particular character. A Spider-Man fan wants to play a Spider-Man game, not some generic open world or superhero game. Fans of Forza are likely to be much more fickle, going to wherever they think the licensed cars they want and the best racing engine are.
Does Microsoft need characters? No. But it might be wise to think about building some of them up. Other than the guy in the green helmet who you never actually see outside reflections and cut scenes.