design question

[Art]

Staying withing the 10FXXX lineage, why would you build a circuit using a 10F200 when a 10F322 costs only ten cents more?

They aren't really thinking like that, the later chip is a newer generation with features designed to obsolete the former.
There was a time when the 16F84 was the same price as a 16F628 too, why would you want half the memory and less peripherals?
Somewhere out there though, someone would still have been wanting the 16F84 to write existing hex files to.