I do not think the developers looked at WoW at all to make their decision on whether to makes the bikes BOP. They looked at how having crafted bikes fill the market place at low prices would effect the economy. Hover bikes are needed once per character till the much higher levels. If one crafter was pumping these out he could flood the server with them till hoverbikes sold for 200 credits each. Not much of a credit sink. Having a hoverbike craftable until there is a variety to make and sell is just for that crafter an added bonus till they get more of a system in place.