To be fair - you can use Yr 1 gear for all content up to TTK and normal Crucible. Light becomes relevant when you try fighting the Taken, run missions/patrol on the Dreatnaught, daily mission, Nightfalls, IB, Trials, and the higher level strikes. My hope is that if/when the old raids are bumped up in difficulty, they also allow us to bring forward the gear we earned from them. Bungie changes their mind almost as often as the wind changes direction. Wait long enough and it's bound to blow in your direction.