[wwalker3]

I agree that component count and the price of other logic chips were important too. Woz was a genius at that kind of design where you have to do something super-creative to save that last tiny bit of cash.

However, I think I can make a good argument that memory price was the main factor. As a hardware engineer, the only reason you'd ever use tricks like indexed color (palettes), foreground/background color per character (like CGA or the TMS9918), even/odd column color restrictions (like the Apple ][), and all the rest is to save memory.

Once you can afford enough memory to store your full color depth for every pixel in the frame buffer, your display hardware actually gets simpler -- it's just a straight pipe from memory to screen with no extra logic (other than your D-to-A conversion in the old days). No indexing, no complicated bit-packing schemes, no switching of color palettes during horizontal or vertical retrace.

Tons of effort and creativity went into that stuff, but it was all obsolete once memory got cheap enough.