While it is possible to build some pretty elaborate stuff in Minecraft using redstone, it typically requires a ton of space. In addition the game has poor support for sending power up or down.
For example, if you want a building with multiple floors and each room has a lever or button that turns on an overhead light in the room, it requires that the space between the ceiling and the floor above be 3 blocks thick (one layer for the ceiling, one layer of air that the redstone goes in, and then one layer for the floor of the room above). This is a tremendous waste of building space. And if you are trying to create something that incorporates an if|then|else structure, it's going to basically require building a room just to handle that.
The solution is obvious. Allow all solid, non-transparent blocks to have two versions: for wired vs. non-wired. You make a block wired by putting it in the crafting table with redstone. What comes out looks the same (or perhaps has a small 2x2 pixel redstone bump on each surface to denote that it has changed) but is named something like "oak wood planks (r)" with the r meaning it has redstone embedded in it. A block that is wired, if receiving power from any one direction, outputs power in all 6 directions. So a chain of these mixed in with the regular blocks in your floor/ceiling allows redstone power to be sent along that line. And the floor/ceiling only needs to be 1 block thick instead of 3. And you can send power up and down without having to use some wonky work-around.
I am not proposing to replace the redstone system we have already with this. I don't want to break existing stuff people have built. I just think they should add this in addition to what we have now to allow for redstone that is cleaner, more compact, and more easily hidden.
Although I think your idea is somewhat intriguing I do want to note that it doesn't have to be 3 blocks wide, I could probably do it with 1 empty space in between (to place redstone dust). Of course I would need some space 'elsewhere' to build myself a small contraption
But on the other hand: I doubt anyone would like to see all those glowing lines running through the walls all of a sudden. So you'd still have to do some hiding of the stuff. And then I no longer see the advantage anymore, at least not in this example.
Doesn't mean I don't like your idea, but I am a bit indifferent to it.
That's what I meant, sorry if it wasn't clear. You have one empty space between the ceiling and the floor, which themselves are one block each, so 3 blocks total.
Also, I was not expecting the blocks to have the signature "redstone dust glow". However, that does bring up an issue, which is that you want the blocks not to show the glow, but at the same time that makes it hard to know which blocks are redstone-wired later on.
I would solve this problem by making it so that when you are holding redstone dust in your hand, it causes the redstone-wired blocks to glow. Otherwise, they look the same as their non-wired versions.
I'd like to see the idea of the integrated circuit added to Minecraft so that custom logic wouldn't take so much space and could be reusable. We need a special table that can create, edit, or clone IC blocks. When being used it should let the player enter an empty expanse and build. Whatever blocks are the furthest in their direction ( Up, Down, North, South, East, West ) should be assumed the edge in that direction and able to input/output with touching blocks on the corresponding sides of the IC. The resulting IC should always be 1 block in size and it's texture should reflect which sides are acting as inputs, outputs, or both and maybe include a short generated code that would reflect the inner-working of the IC (digital signature of the blocks contained) such that any two ICs with the same inners would always have the same code.
Perhaps you are overthinking things. Something like what you suggested will not be possible to implement in any edition of minecraft. However, they did replace commands blocks with actual functions in recent versions of Minecraft Java Edition. It might help with what you want.