All names taken, whilst not wanting to see the train spotters take over the thread, rail connectivity is very important to any airport that has it, as is any form of surface transport. With the developments around the airport the rail link assumes even greater importance and common sense would say that a way should be sought to extend the link to the cargo centre which would allow it to become a multi modal centre.
As for Birmingham, back in the late 1990s it was reported that less than 20% of Birmingham International's passengers used the airport, its clientele being primarily NEC generated. I doubt that has changed significantly.