Unless you work with the media related aspects of the Amiga, such as graphics, animation, programming, musick, etc. Then you will probably be more likely to say that Amiga consists of the software.
Once you begin creating things on the Amiga, and compare that experience with creation on another kind of Computer, you'll feel the difference instantly! Also UAE can not pull off OctaMED Sound Studio correctly, and it sounds like it never will. Again, hardware is where it is at, though...
I love the idea of taking the Software side of Amiga and bringing it to modern, more powerful hardware to take advantage of those aspects of Amiga that did not rely upon the custom chip set to execute.
In short, Amiga is the sum of it's parts. MorphOS is a parcel of those parts, as is OS 4. Provide them with the Custom Chips, and they become a full fledged Amiga, with them chips, they remain a brilliant shadow of what was.
On that note, wouldn't it be cool if we could buy the Amiga Chipset on a PCI card to install into our towers...