This game is running on a new engine so you can expect the source code not be the same either. Which is kinda like having a new game. Sure they could transport assets from the old version which is a huge timesave not having to remodel everything. But otherwise the relaunch would have taken 3+ years.

In the end sure I agree CT should have been available from the start. The more content available the better but in game developement stuff happens not everything goes as planned. Personally I see CT as a possibility to equip your other jobs. Is this ideal? No but hey better than nothing.