Quote from joonatan1998
I think that having more than 16 levels of light would increase the lag, mods that add new light sources usually make the lamp block spawn invisible aditional "lamps" around it.
But if Mojang did it, they can simply add a bit of code that allows for light sources to have a higher value and just extrapolate that into their functionality. I assume the most difficult bit would be to make their value use a larger variable size, instead of the 4-bit variable they probably currently use. Modders have much greater difficulty because they are working with a lesser modding interface than what Mojang works with, they have less experience with the code, and also many if not most of them want to make the mods compatible with unmodded gameplay. A change as I am suggesting would not allow multiplayer play with a client that had not been updated yet.