why?

because new features always going through the decisions:

"do we need a new extension for that or not?"
when CT extraction was added halfway through beta, the decision was:

"yes, because if don't add more extensions, industrial player will be skilled out after 1 year"

- but about your concern:
I wanted to start a topic about this extension today too, for several reasons:

• description is unclear. nowhere ingame is mentioned how much a CT degrades on extraction.
  prior point-system, it randomly degraded as if you would run 1 cycle. (guess)

• now regular CTs degrade from 0.3 points to 3 points per cycle, and they dont get destroyed when reaching 0 points! IMHO that makes this extensions effect kinda useless fo that production

• Foundation CTs degrade in huge jumps - the extension would make sense there (at what it does) in theory - but those CTs reach zero in just a few cycles, then you can extract them without penalty and refill them in CT-Lab.

so, summary: This extension should be removed just like the paralllel assignment extension (which is another dumb one)