It's likely someone designed this on their coffee break and it didn't cost much to implement. Might even have just been some sort of software change that was free. I would also rather see performance updates but little things like this don't hurt anything. More people would probably think this is ok if they hadn't mentioned the pony heartbeat. Now if a voice said "Ready for ignition" when I opened my door I might have a problem. But this really has no effect on anyone other than to highlight where the start button is. First world problems indeed..
Automotive Engineer: We've determined that pulsing the start button led every 1/2 second will indicate an accessory position, or ready to start condition".
Marketing Babe: "I was grooming the pony my dad bought me for my birthday the other day, and noticed his little heat beat dropped to 30 bpm, I think it calmed him".
Maketing Executive: "Heart of the Mustang, 30 beats a minute, stop the presses on the sales media, Do it"!!!