One man's cheap'n'nasty is another man's elegance. And $0.50 was a lot of money back in those days ;)
Anyway for computers of the era that generated TV output, it seems like it was common to start with whatever clock speed was necessary for the video output, and work back from there. Hence the odd CPU speeds of the C64, Amiga, Atari 8-bit, etc.
For some real excitement, look at how the Apple 2's graphics worked. If you ever worked with hi-res mode you know how screwey the colors were. Turns out they basically serialized the bits right out of ram into a crude NTSC signal and the bits ended up making different frequencies--hence different colors (the high bit of each byte specified whether to delay the rest of the 7 bits by half a clock).
Looking at an Apple 2 schematic is eye-opening. There's hardly anything there!
Anyway for computers of the era that generated TV output, it seems like it was common to start with whatever clock speed was necessary for the video output, and work back from there. Hence the odd CPU speeds of the C64, Amiga, Atari 8-bit, etc.