I have an idea, involving changes to the lighting system.
I think it would be good to add different coloured lighting to Minecraft, obtainable by using coloured glass blocks/panes, other partially transparent blocks, and sea lanterns and magma blocks giving out slightly bluish/orangey light. The debug screen, instead of showing just daylight and block light, on a scale of 0 to 15, could instead show the average colour for the player's position (in hexadecimal. e.g. '#FFFF00', for yellow), for the block light, and the daylight, and then an overall strength of light (0 to 15 or as a percentage). If there are two coloured glass blocks, placed at opposite ends of a corridor, with lights behind them, the colours would merge, (a red glass block at one end and a blue one at another end would give a colour of around '#FF00FF', and the strength would depend on the distance to the middle. The colour code would not include the lack of light due to distance, only the strength would.
It would be an improvement on the variety of effects one could create by using different light source blocks, and I generally think it should be considered.