Yeah, but how often do you say "computer" in a querying/interrogatory tone?
That's a perfect opportunity to get better at cosplaying a Starfleet officer.
(Seriously though, a Federation-grade system would just recognize from context whether or not you meant to invoke the voice interface. Federation is full of near-AGI in simple appliances. Like the sliding doors that just know whether you want to go through them, or are just passing by.)