Why JB was chosen for logistic centre is because of cheap land to build huge storage warehouse but most important factor is the close proximity to the a major international aviation hub, Singapore.
That's why they chose JB and not KL!
These days, efficient logistic centre uses smart machine, robots, etc. with few workers to do the job.
There will be some new jobs created, a few executives and engineers but mostly will be jobs like admin staff, drivers, couriers.
As I've always said, this is what JB is good for and should capitalize on it.