I think you have completely underestimated the competition in the market nowadays. People who buy smartphones these days, expect them to be update-able with the latest features, even mid-end phones receive attention by for example Sony or Samsung when it comes to new Android builds, and Apple has made it a "feature" to still support relatively old products with new OS releases. HTC was been losing an extreme amount of customers because they didn't care about updates. Because they fell asleep in the competition.
Of course people will lose faith in Nokia extremely fast, if they leave out purely software based features such as "double tap to wake". I like my 720, and don't need this feature myself. But for professionals, Windows Phone 8 is still very much a "beta" OS, with very basic features lacking. For example how one would adjust the ring volume independently of what the volume level was set to the last time you played a game or listened to music. My Sony-Ericsson W810 from 2006 had this feature!
When pushing the "turn off screen"/sleep button during a game, for example Asphalt 7 or Rayman Jungle Run, the game is completely messed up when waking up the phone again. Again a very basic, but illustrative example of what state WP8 is in.
My point being that Nokia does NOT have the privileges to "leave" out simple features on such a new phone which already lacks in comparison to competition. It is as simple as that.