Satanus - Well the JW bible is not like the other bibles so I suppose spew green, bought at an extra cheap price may well have been an attractive offer!
My mother insists on still using her 'green bible' even though some elders have made subtle hints that she should buy a new one.
However, as Blondie points out, the translation may have had 'spiritual' assistance but the colour........I still remember the comments on that.
I will try to find out about 'the green'. I just thought someone might know more about this.