There are a whole lot of factual errors here, or at least conclusions kind of pulled out of thin air. To wit:
> This may well be true, but my own suspicion is that it had as much to do with Apple having hundreds of core system developers already familiar with the C++ APIs, and a limited timeframe to get Mac OS X released.
Actually, NeXT already had a perfectly cromulent Cocoa-based "Finder", called the Workspace Manager. This was the program used in NeXTSTEP and later in Rhapsody. Apple threw it away and replaced it with a Carbon Finder built in-house. They were quite specific as to the reason: to guarantee that Carbon was bullet-proof, Apple built the Finder "to eat their own dog food" (though he didn't originate the term at Apple, I think Steve started using it too).
> [regarding UFS] In order to maintain compatibility. And it wasn't just ported code -- HFS+ support was rewritten from the ground up as a UNIX file system. Surprisingly, the result wasn't a delicate hack, and the fact that we're still using it today (on iOS too!) speaks to the engineering capability of Apple. (And NeXT, since it's all one big family now.)
It wasn't just compatibility. Though it was case-preserving :-(, HFS+ had some big advantages over UFS. It supported Unicode. It supported metadata. It supported soft links which were preserved in removable media. It had much better networked file support. And so on.
Also: IIRC HFS+ wasn't rewritten from the ground up. Apple already long had a version of it running on UNIX systems they had developed in-house.
> Quicktime was also ported to Windows.
The point is, NeXT already had a multimedia, sound, and (limited) video system. It was famous for its sound system in particular. But (Carbon) Quicktime was better. So they used it instead.
> In order to maintain compatibility. The recommended way to write games on Mac OS X has always been the OpenGL APIs, and you can hardly describe OpenGL as a legacy Mac technology.
You absolutely can! Porting OpenGL involves a huge number of low-level ties to the operating system. NeXT had its own 3D facilities as well (OpenGL under NeXTSTEP, and Display Renderman), which were entirely tossed out in favor of the "legacy" OS 9 version.
> Java came from Sun.
On early OS X, the bulk of the Java facility came from Apple. Sun didn't support the Java port at all. NeXTSTEP, or more properly OpenStep, had a Java port from Sun which was entirely replaced with the OS 9 Java version.
> Font handling in Mac OS X is part of Quartz, a new technology developed for OS X.
Not correct. Font and typographic engine technology was derived from ATSUI, Apple's advanced typography system. And why wouldn't they? It was the best in the world.
Look, I don't dispute, by any stretch, the notion that the crucial parts of OS X were NeXTSTEP. I'm a NeXTSTEP guy! But your dismissal of Carbon and OS 9 technologies that found their way into OS X is both overly casual and in many cases simply false. To this day OS X still has a huge number of OS 9 technologies embedded in it not because of compatibility, or just because of compatibility, but because they were the best technology. Apple's not stupid.
"It was famous for its sound system in particular."
I don't recall it being a big deal after the black hardware and their DSPs were killed.
"NeXT had its own 3D facilities as well (OpenGL under NeXTSTEP, and Display Renderman), which were entirely tossed out in favor of the "legacy" OS 9 version."
I don't recall NeXT ever having OpenGL. And Display Renderman pretty much lost to OpenGL in the 90s, so that wasn't about to be resurrected.
" NeXTSTEP, or more properly OpenStep, had a Java port from Sun"
As I wrote one of the more popular sound editors as an undergraduate (Resound), them's fightin' words. SoundKit was still quite good, even if MusicKit sorta died with the DSP.
I think I'm mistaken about OpenGL, my memory is fuzzy. As to Java: what I was thinking of was OPENSTEP/NT and NEO both supporting Java (WebObjects had Java as early as '97), but I believe it was never released on NeXTSTEP. I guess that doesn't count.
I do miss Renderman on the desktop. Maybe not very practical, just really cool.
When I was contracting at Swiss Bank in Chicago in 1994, I noticed an HP on the network running NeXTSTEP. I telnet'ed to it from the NeXTStation on my desk, and ran some renders to see how much faster it was. Got a stern email saying "Stop doing that.".
> This may well be true, but my own suspicion is that it had as much to do with Apple having hundreds of core system developers already familiar with the C++ APIs, and a limited timeframe to get Mac OS X released.
Actually, NeXT already had a perfectly cromulent Cocoa-based "Finder", called the Workspace Manager. This was the program used in NeXTSTEP and later in Rhapsody. Apple threw it away and replaced it with a Carbon Finder built in-house. They were quite specific as to the reason: to guarantee that Carbon was bullet-proof, Apple built the Finder "to eat their own dog food" (though he didn't originate the term at Apple, I think Steve started using it too).
> [regarding UFS] In order to maintain compatibility. And it wasn't just ported code -- HFS+ support was rewritten from the ground up as a UNIX file system. Surprisingly, the result wasn't a delicate hack, and the fact that we're still using it today (on iOS too!) speaks to the engineering capability of Apple. (And NeXT, since it's all one big family now.)
It wasn't just compatibility. Though it was case-preserving :-(, HFS+ had some big advantages over UFS. It supported Unicode. It supported metadata. It supported soft links which were preserved in removable media. It had much better networked file support. And so on.
Also: IIRC HFS+ wasn't rewritten from the ground up. Apple already long had a version of it running on UNIX systems they had developed in-house.
> Quicktime was also ported to Windows.
The point is, NeXT already had a multimedia, sound, and (limited) video system. It was famous for its sound system in particular. But (Carbon) Quicktime was better. So they used it instead.
> In order to maintain compatibility. The recommended way to write games on Mac OS X has always been the OpenGL APIs, and you can hardly describe OpenGL as a legacy Mac technology.
You absolutely can! Porting OpenGL involves a huge number of low-level ties to the operating system. NeXT had its own 3D facilities as well (OpenGL under NeXTSTEP, and Display Renderman), which were entirely tossed out in favor of the "legacy" OS 9 version.
> Java came from Sun.
On early OS X, the bulk of the Java facility came from Apple. Sun didn't support the Java port at all. NeXTSTEP, or more properly OpenStep, had a Java port from Sun which was entirely replaced with the OS 9 Java version.
> Font handling in Mac OS X is part of Quartz, a new technology developed for OS X.
Not correct. Font and typographic engine technology was derived from ATSUI, Apple's advanced typography system. And why wouldn't they? It was the best in the world.
Look, I don't dispute, by any stretch, the notion that the crucial parts of OS X were NeXTSTEP. I'm a NeXTSTEP guy! But your dismissal of Carbon and OS 9 technologies that found their way into OS X is both overly casual and in many cases simply false. To this day OS X still has a huge number of OS 9 technologies embedded in it not because of compatibility, or just because of compatibility, but because they were the best technology. Apple's not stupid.