Invisible/discrete lighting

Either using glowstone dust or some glowstone product you can cause blocks to emit light up to level 15 with no source or an added texture that is discrete.

You can use glowstone dust (right click) on blocks and it will glow at light level 4/8/12/15 depending on how much glowstone you use, and it can be washed away with water. (The glowstone can either be gone or appear as an item)

You may see this as op, but lighting in general is extremely cheap and only serves two purposes. prevent spawning, and adding aethstetic/visuals. Spawning prevention will continue to be done with torches as it is cheaper and this will only add to builders ability to create aesthetically clean and thematically accurate builds. 

There is no reason not to do this as it also makes sense lore wise. Another benefit is that if you want you can cause everything to have a light 8 which will give you the ability to have a darker theme without spawning creepers in your build.

Thank you.