I think this is a good middle ground on the armour affinity problem. Bungie will most definitely not remove element affinity as a whole but the ability to change the element of a fully masterworked armour piece (for a price of course) sounds fair to me considering the amount of time and investment required to get 10 energy. Same should go for weapons and their masterworked stat boosts. Currently getting an armour piece with amazing stats but the wrong element is a crushing feeling and does not encourage grind, instead it promotes lack of player intentionality.