In a word: manners.
In particular, cell-phone etiquette.
How many times have you been annoyed by somebody talking on their cellphone, at some very inappropriate time and/or place? With Siri/Iris/etc, not only are you given multiple opportunities to hear the caller talk loudly about personal issues you really didn't need to know about, you get even more opportunities to hear the smartphone owner ask all sorts of questions, thus increasing verbal pollution. And if you're really unlucky you get to hear Siri/Iris answer back in their sweet, artificial voice.
Oh what fun.
The more I think this through, the more I believe that any voice-operated input on a smartphone is a boondoggle, yet another useless gotta-have-it-feature created by cynical marketeers for a gullible buying public.
Via: Cell Phones