That Thunderbolt is provided by additional ASIC, not incorporated in the chipset. The basic problem with Thunderbolt implementation is it's price - $25 per chip. Intel is the sole provider of the Thunderbolt controller. It is not licensed to anyone.
What I've heard about additional features is that mobo vendor tend to like them , when their price is $1-$3, $5 max. Thunderbolt is much pricey than $5, so nobody likes it. It is that simple.