TBH I think you are underestimating the practicality of it. If we are co-working or co-inhabiting with non-static entities, this becomes a much bigger concern. There is a reason industrial robots are generally in safety cages, with rapid shutdown any time the safety boundary is crossed by a human.

Option 1 - my home robot makes a sudden movement, catching me off guard, and smacking me across the shins (or worse).

Option 2 - my robot loudly announces "warning, moving to the left in 5, 4, 3, 2, 1", which drives me insane after a few days.

Option 3 - my robot taps into a million years of non-verbal communication that humans have evolved, and indicates what it is about to do both with more subtle audible and physical cues.

PS: regarding "display attention" - trivial example, "hey assistant, remind me to do X on Sunday"

- option 1: no attention display, I have no idea whether my request has been recorded

- option 2: verbal or auditory or physical cue that assistant is listening, and a cue to confirm that the request was processed successfully.