Urks twitter "I didn't say anything about a level 20 cap during the interview" For all we know we can level our guardians to level 100 and each game we get scaled back. Can't say otherwise as destiny has consistently showed us a new way to play a fps with destiny. The second everyone thought the cap was 20 every bungie butt hugger came out of the woods trying to defend bungie regardless of whether or it was good for the game. Even watched videos defending it I'm aware of light and leveling armor and progressing your character past levels in just saying be more open minded about if something is a good idea don't just hop on w/e bungie may or may not think is a good idea.
It's been stated that they are promoting a 'horizontal' model of leveling. We'll hit the cap rather low then grow our Guardians via gear and abilities.