There is always the chance that as we get better at this stuff we'll start to find it creepy that it's so realistic (either due to the uncanny valley or because we crossed the valley) and we'll start to prefer devices that act robotic even though we know we could make the indistinguishable.

I'm trying to think of another example. I know I've heard a good one with Roombas but I can't remember it.

Basically we may try to avoid a Bladerunner situation where we're not sure when we are or aren't talking to a real person and prefer the 'computery' voices.