Because those things aren't useful, would be my first guess. Particularly the latter; that's just creepy.
i would probably throw my toaster at the wall if it sang at me in the morning
Opera Singing Toaster: "LA LA LA YOUR TOAST IS DONE LAAAAAAAA!"
LOL! No doubt; I had a mental image of a toaster vaguely resembling the singing sword from Who Framed Roger Rabbit smashing against a wall xD
Invisible chairs sound like a great idea
I think holographic chairs sound even better hehehe :D
I want a singing toaster now. XD