Imagine if there were individual blocks that displayed entire characters 0-9, A-Z, and the most common non-alphanumeric characters, including commas, apostrophes, and the three punctuation marks. Not banners that look like letters. Those are difficult to make anyway and they take up 1x2 blocks, rather than just 1x1. I mean you go to a stonecutter (or possibly an entirely new crafting station altogether), insert either concrete or terra cotta, apply ONE serving of dye onto them, and immediately choose from a list of possible letters, and out pops a version of that concrete/terra cotta background with the letter on all six sides that displays the character you chose.