They said they cant do that because they've have to revise every mobs loot distribution. Its kinda in the OP
To give a bit more insight, the development team looked into a completely different direction on this at first, exploring if they could establish proper balance to follow this idea by changing the drop rate table. However, if they were to change the drop rates, the obtainment rate for every single item would change and the effects would be too drastic, so they came to the conclusion that they would not be adjusting the drop rates.