Hmm, nice idea... but surely blind users would be able to identify the location of the headphone socket due to it being a hole in the top of the phone?
If you have an iPhone, close your eyes, set it on a desk and spin it around. Now find the headphone socket. You have a 50% chance of trying to insert your headphone pug into the speaker hole or the screw hole next to it.
On the new model, run your nail down the short edge, as soon as you catch on the 'seam' you know the socket is about 5mm beyond that.
I know it could just be ornamental, but Apple's DNA seems to only include design elements that have a function, ie. Dieter Rams 2nd rule of good design.
M.