The problem is that most gamers' complaints lies in Destiny's main elements like the RNG, special weapons, supercharges... etc Making drastic changes on these things will have a huge response depending how good or bad it is. Since Bungie don't want to risk having a huge negative response toward their game, they will play it safe for now and focus on the DLC hoping that they could redeem themselves. Then again, this also have a negative effect on Destiny since it is overshadowed by a paywall.