I am by no means an expert at this but I think the main reason is that it is too expensive for a lot of people to do. Leaves are cheap and work great. 3 and 4 links with coils are a little harder to get to work properly and are more expensive. Plus I really dont know of a company that sells these kits (with a reasonable price tag). these are just my observations and not fact at all...
Personally I would love to have a linked setup in the front of my rig.
