I didn't say it's a good or useful feature. It is, however, definitely, a matter of "it just works". Most non-Macs "just work" at this point - you touch their screen and they respond. This has been the case for about a decade. A lot of people born in the last 14 years have never touched a screen and seen it not react.
The mac, for them, feels like a cheap relic of the past. It's covered in skeuomorphic images, mimicking what you see on a tablet or phone, except you can't actually touch the buttons on it and instead you have to use the mouse.
Do you need to touch the screen? Obviously not. You don't need the speakers, either. But it's incredibly weird and cheap that it does nothing when you touch it. And it gets weirder everyday, as a growing portion of the population doesn't remember when multitouch capabilities weren't standard. Of course, these people don't remember when Apple devices "just worked" either.