This was inspired by this thread, feel free to check it out!
I'm suggesting that a block called the "light block" is added to the list of /give only blocks (command blocks, barriers). It would not take up any space when placed, but would act as a light source, the same strength as torches. If a block is later placed on top of where the light block is, that block would emanate light as well, as if it were a torch. As it is invisible, it would act like barriers and would only be visible if you were holding the block, and would have a small torch symbol on it, in yellow. Also, you could only break it when holding the block in your hand, since otherwise it could be extremely annoying for creative builders. I'll make the texture soon, and if this gets any support I'll add it to this post. Thanks for reading, please post below, and vote on the poll!