It's a FEAETURE, u like it then u turn it on , u dont like it , then just switch it off , we dont bias it and call it as a rubbish or useless feature because we dont use it while it might be super useful feature for somebody
especially u are busy in the kitchen , u washing plate , u cooking something , ur hand is full of dirt , u washing the car and full of soap ,...with AOD, u just put ur phone on the table and don't need to touch ur phone and u can get to know the time....because sometime u will be in rush , so u need to keep on monitor your time to done the task , with AOD u dont need keep trigger up ur screen just to look for the time.

Not to mention  , AOD is super useful when in meeting room , because u can directly look into your clock time without keep touching ur phone...

And not everyone like to wear a watch and i dont think modern house nowaday like to hanging or having CLOCK in house....