Cymric wrote:
1. Measure time with a greater accuracy than 55 ms. Amigas have CIAs which provide microsecond accuracy.
At least on more modern systems, the OS will usually give you down to 10ms resolution. The PIT is theoretically capable of going lower, but it's inefficient to do so (interupts are expensive on modern processors and reading from the PIT directly rather than counting interupts is slow for other reasons). If you don't need to trigger interrupts and just need to measure time the ACPI PM clock has sub-microsecond resolution.
3. Display an image based on bitplanes. (Then again, the Amiga cannot really display a chunky image without employing advanced Copper trickery, and then at great loss of resolution. The entire concept is alien to the Amiga hardware, is what I'm saying.) This made the Amiga perfect for sideways 2D scrollers, but absolutely not perfect for 3D games.
I don't know if the Amiga bitplane approach is really ideal for 2D games. It makes sense in the context of the computer as a whole (i.e. it's not just for playing games), but most 2D graphics hardware in games consoles used tiles made up of 4-bit (and in some later incarnations like the Saturn 2D hardware 8-bit) chunky pixels. In a modern computer bitplane based displays really don't make any sense as there isn't any real reason you'd want your display to operate at less than an 8-bit color depth anymore.
2. Generate raster interrupts the way the Copper can.
4. Attach 9-pins joysticks and mice with ease. (You always had to use a 15-pins port.)
5. PCs do not have standard hardware support for light pens and potmeters. Then again, who uses a light pen nowadays? (I had this one for my Schneider CPC464---very nifty and cool toy.)
I don't think these are terribly relevant anymore. The Amiga has better handling of floppy disk hardware too, but hardly anyone would care now since USB flash drives are superior in just about every conceivable way.
6. Nor do they have standard support for analog TV out signals (it depends on your video card) or genlocking (which is now handled in a different way).
I don't know if you can really say the Amiga exactly had standard support for analog TV signals. The 2000 only supported mono composite without extra hardware and the 4000 didn't have any analog TV output at all without extra hardware. TV-out is more or less a standard feature on laptops these days and is reasonably common on desktops too. Of course, none of them support genlocking, but as you said that's a feature that's not really relevant anymore.