I am a member of an email group that often receives posts sent from member's mobile phones. While I don't think they can stop it happening, and so I don't thing they are aggrandising themselves for having an iPhone, there is a footer that comes with the email saying 'Sent from my iPhone'.
I don't have an iPhone and I can email without my phone adding, 'sent from my Ultra Touch'.
It rather reminds me of when Volvo cars always had their headlights on when being driven. There was nothing the owner could do to stop the lights being on, and given the general standard of driving by Volvo owners, it wasn't such a bad thing. Volvos no longer compulsorily have their lights on and I suspect in time, 'sent from my iPhone' will disappear too.
Who could forget the very loud turn signal noise on motorbikes. Don't seem to hear that now either.
The next microwave oven we buy will definitely not have the 'nag' feature. If I am stupid enough to forget I have put something in the microwave, then it is my bad luck. I don't want three piercing beeps every minute to remind me. Mind you, there will probably always be a cup of warmed up coffee gone cold in the microwave that I have forgotten about.
Do you have some auto thing happening with your bits of electronics or car that you hate?