Impertinent Question...

[nasadowsk]

My guess is that the tooling to do another size was just insane. Remember, they were barely selling any color sets in the 50's, and color CRTs were not a simple manufacturing process. B&W was just a different envelope and maybe a somewhat different gun, and you'd easily sell as many of one size than the entire yearly sales of color. Color? Different mask, different jigs to coat the screen, different gun, different convergence assembly, etc etc etc.

I wouldn't be surprised if the cost difference between a smaller size and a larger one would be minor - the color section's the same, the CRTs required a lot of hand work to make...