The suspension of the staff bus has less to do with the environment, and more to do with saving money. A study was done, and it was found - not surprisingly - that usage during most of the day was low, with just a few people on the bus at any one time. However, I doubt very much if anyone bothered to log the numbers using it between 5am and 7am, which of course is also the peak time for the passenger buses.
A more sensible compromise would be to have the staff bus running only at peak times, making life easier for everyone.
By the way, it's not just EMA employees who use the car park next to the terminal, some senior managers of handling agents etc, use it too.
R5