There's no practical reason for most people. Spying is the primary function. Edge cases like accessibility or conferencing can be easily enabled with an add on USB mic. You'd need a USB webcam with mic for conferencing anyway.

People use voice commands on TV remotes all the time if they're using streaming apps. At this point it's the default way to interact with the UI for many people.

Typing out the show you're searching for with an awkward onscreen keyboard is a huge pain compared to just clicking a button and speaking.

HN users are very much in a bubble if it's surprising to learn consumers expect voice control functionality on a new TV.