I wonder if you could clarify a bit the difference between "seemlessly integrated" and "embedded"?
My mouse is seamlessly integrated with my computer, but it is not embedded. It interfaces effectively through a standardized protocol and could be replaced with an other device that offered the same functionality over the same standard interface.

But it seems to me that the main point is removal of IE causes loss of functionality as you have said.
No, the reason that functionality is lost, to continue the mouse analogy is that IE is like the only two button mouse on the market. Anything you replace it with would a Mac style one button model. Clearly you will lose the capability to use the right click functionality without some sort of work around. The same is true for replacing IE with another browser, you lose functionality because those other browsers are simply less functional.

I could say that the pistons in my engine were either "embedded" or "seamlessly integrated," but either way, if the pistons are removed the engine will not work as designed.
The pistons are part of the core engine, more akin to kernel drivers (the block would be the kernel). The computer will still work without IE, it will just lose some functionality that is offered by IE.

Getting back to software, I can install Opera and then uninstall it from Windows without breaking any functionality.
If you don't have another browser, you lose the functionality of web browsing. If you replace it with a different browser, you lose any functionality unique to Opera. The issue is that Opera isn't that functional... it is just a web/email/torrent client, where IE offers the functionality of working with Explorer and help and Windows Update, etc.

cheers,

catch