It's making a niche rarely done use case safer at the cost of making the common case (browsing the web) less safe.
And yes, I am fully aware that I can not press the button that give random sites access... But the issue is it increases the attack surface and is yet another thing that I could get tricked by on a bad day.
The OS should really be able to run code like a firmware flash utility in a sandbox that only has access to one USB device... But instead of improving the OS we keep adding features to the browser which increases the attack surface.
I have a very long list of things I am unhappy about the OS allowing just any app to do, especially app installers/uninstallers should not be a thing.
That's what I do and that's what I suggest for any security-conscious user to do. Just explore Chromium settings, there are dozens of various APIs that could be disabled. Do you need Web MIDI? I don't. Disable.
Won't work as a default setting for average user for sure, but if you consider yourself an advanced user, do that.
I could understand it if you were trying to do realtime configuration of or interaction with some device like a printer or a Stream Deck, but something as trivial as firmware flashing?
Yes, you could make the configuration into a separate uf2 object that overwrites other bytes, but that's yucky.
The access is explicitly per device. Even for plain flashing, it's safer and simpler than to download and shuffle random files.
With WebUSB implemented in major browser, you can be sure that they took extraordinary attention to all security implications.
With some random application from tiny developer, can you be sure about that?
I know for sure, that I prefer a webpage isolated in the browser for anything that could be done in a browser. I'm very hesitant to install anything locally.
Even for local apps it's starting to become common to ship the app in an interpreted language where the interpreter is a browser instead of say python & qt.
But please don't tell other people what they should and shouldn't do on their own hardware.
The world has enough corporate walled gardens. I even enjoy using some of them sometimes, but the world would be a strictly worse place if these were the only remaining way to use computers.