Airborne Effectivess is a new way to customize your character. It gives players an incentive to use underutilized exotic amors and weapons. It helps standardize Airborne accuracy, and the next update will make the stat viewable on weapons. Finally, if you spec into it, you can become more accurate in the air than ever before. Flinch while sliding makes sense considering that sliding from cover was the dominant form of play for a long time. It is still dominant, but now there are some minor disadvantages to doing so. There have always been abilities that counter primary weapons in the Crucible, such as Healing Rift and Healing Grenades. Why are you complaing about things that have been in the game for years?