The older colour LCD's, specifically CSTN (colour STN) used an 8-bit interface that was a bugger to use - RGBRGBRG... BRGBRGBR .. GBRGBRGB (first 8 pixels, only 3-bits per pixel). One would usually use a dedicated controller for such a display, such as the Solomon Systech SSD1906 which acted both as the controller, frame buffer, and contained programmable colour palette's. Different colours were achieved with frame PWM, and dithering (as it was a passive display, pixels can only be turned on or off). I believe the gameboy display had a controller that did something similar built into the flex cable.
I implemented my own controller than barely fit on an XC95144XL cpld. Totally not worth the hassle.
Since TFT's have become ubiquitous and cheaper, and MCU's have got larger, cheaper, even with graphics controllers (the basic frame buffer/refresh) built in, there generally isn't much call for external graphics controllers or making displays with built-in colour palettes. As TFT's just have that parallel interface for each pixel, the user has full control over colour directly.
If you want to use a TFT in your 8-bit projects, I'm sure there are 8-bit/arduino friendly TFT modules that have the TFT display and a built-in MCU to handle the nitty gritty - colour pallete, shapes, lines text etc.. Or you could roll your own with a 32-bit device, but then you might as well use that for your projects eh