Increasing the MW core drop rate is not the answer. They are at a good rarity for masterworking weapons/armor. If you increase the MW core drop rate for infusion, you in turn increase it for masterworking, which undermines that grind. The grinds for masterworking and infusion really need to be separated. Bungie should just remove MW cores from the infusion cost. The week before forsaken dropped they had planetary mats and increased legendary shards for the infusion cost, and I think that was the sweet spot.