Consolas is not bad. DejaVu is not bad. Only Courier/Courier New are so bad as to be unusable, it seems Apple wants to push web developers to use font overrides.
Newer releases also have San Francisco Mono that it could use instead, which is even better since it's tuned for modern displays.
Though of course there are plenty of discontents with that. On balance I think the apps that ship with MacOS are much worse than their Windows counterparts. I think iOS on the iPad is truly superior but the settings app is dark pattern city, particularly the notification that never goes away about the Apple TV trial that is about to expire but actually expired years ago.
Even having some defined meta fonts with rough metrics so that you could say font-face: monospace-standard or whatever and have the text be roughly the same size everywhere would save so much effort and wasted data.
Including a small set of open fonts does seem like a good idea. I'd like to see Inter UI[0] included because it's a very nice screen/UI-optimized font would serve a similar purpose as "system-ui" does now, except without some of the pitfalls[1] that comes with.
[0]: https://rsms.me/inter/ [1]: https://infinnie.github.io/blog/2017/systemui.html
But no browser defaults to Courier New any more—Firefox on Windows was the last browser to finally update to a better font, just under a year ago (see https://bugzilla.mozilla.org/show_bug.cgi?id=1607913).
I fucking can't stand Consolas, give me Courier New because that font is readable literally anywhere.
Courier New is the most appalling piece of shit I've ever seen in my life. It's ugly at small sizes, jagged and unpleasant at medium sizes, and abhorrent at display sizes. WOW do I hate Courier. I hate it on Git Bash. I hate it in cmd, I hate that it exists. Consolas, by contrast, is lovely and beautifully-hinted at best, and inoffensive at worst.