What did Werner Heisenberg say, "What we observe is not nature itself, but nature exposed to our method of questioning." There are other methods to getting multiple focus, like simple burst shots at multiple focus points, or aperatures. They all cost TIME. As one poster said, the amount of directional data you need to collect would necessitate a huge sensor and the large the sensor the slower the camera (to process the data).
For serious photographers, they'd rather make a quick judgement of focus shots and aperature than wait for a camera to get enough data to change later.
Heisenberg might point out that you can either get prepared to take another shot in 1 second, or wait for the previous shot to get all the focus points, but you can't do both.