I seem to recall one of the producers -- Gene Roddenberry, or maybe Bob Justman -- saying the only reason he was in the pilot's chair was because of a private joke about "having a blind guy drive the ship".
the characters changed massively in the subsequent seasons. It does seem to me that promotion to Chief Engineer instilled a sense of responsibility into Geordi. It was quite a natural development (indeed, possibly a better development than some
of the characters got, *cough* CommanderRiker *cough*).