Roblox's UWP Microsoft Store app, for instance, still uses the old legacy EdgeHTML based webview.
... While I mention Roblox, let me just let it be known that the win32 Roblox app, the one that Roblox pushes, uses an incredibly insecure IE webview. Roblox simply doesn't listen to feedback.
The Xbox app is not a good indication of RNW performance, by the way. It's like what Slack or Teams is to Electron. According to Microsoft, they don't have any external clients yet. Nor any internal clients apart from Xbox, and now Windows. That means there is no VS Code of RNW just yet.
But anyone can tell you that RMW apps won't be as performant as a native app, such as a WinUI app.
What do you mean by "now"? Did something happen this month? WPF and WinForms haven't seen much at all for... a long time. This comment sums it up well: https://news.ycombinator.com/item?id=29424984
But there's no distinction between a security patch and a feature update. And it's never just an update to only get new features. It's to get bug fixes and better compatibility with new programs (I'm thinking of libraries and dependencies). And there's the case of Windows and Chrome OS, where software updates cannot be opted out of by official means.
When I think of planned obsolescence and sorta-unintentional performance regressions on desktop operating systems, I'm instantly brought to YouTube's Polymer website and UWP. Two complicated things but they largely only benefit the developers of the software and have not actually delivered any features. Google is a huge part of the desktop world and they're not so "external" as pabs3 says and to me it's just part of the software right to repair movement.
For me Task View was the biggest improvement. It's more or less a few bug fixes. The touch keyboard too. Uhhh that's bug fixes too and most of the changes to it are horrendous, but hey, it opens a bit faster.
I've found the Settings app to require way more clocks than Windows 10's, and as someone with Bluetooth earphones I open the Bluetooth page often. They didn't improve it in any ways that affect me and only added more clicks.
Most of the improvements I've seen were just bug fixes that were going to be in the next version of Windows 10 before they got the grand idea to use Windows 10X's nasty shell elements. I actually thought the combined system tray might be nice but it was just annoying and requires more clicks.
So back to 10 it was. I'll have to live with the bugs.
They very existence of PowerToys is a testament to Windows's mismanagement. They wrapped search around Wox, an app that uses Everything, to appease users who were unhappy with Windows Search. Microsoft declined to use Everything to power their search, by the way. Most PowerToy suggestions on their GitHub are just Windows suggestions and bug fixes.
I love the example of the Task View to show that they really don't use their own darn things. Since 2018 it has been incredibly buggy. Reproducibly even.
Microsoft has a lot of gaming IP that they'll only release games for on Xbox and Windows. They'll likely try using DRM and anti-cheat to avoid the likes of WINE or maybe they won't even feel the need to. It's just more effort for users anyway. And Riot Games has VALORANT. DRM heavy gaming is not going away but only just beginning.
Off topic, but Microsoft can even bypass Steam and use their own (terrible) Microsoft Store and Xbox apps on Windows as they have hard to resist exclusive content. Just like Epic Games did with their store. Platforms, not services!