Bamboo is so fast growing that it is a reasonable plant resource. Because you can harvest often due to its high growth rate, you don't need to use as much land to produce the same amount of biomass. In turn that means that you can use more arable land for other agriculture.
Soy, which is already grown in large quantities, can be made into fiber that is made from the waste products of the soy food industry. So planting soy can be a good market decision by farmers for selling to the food industry. And in turn it is good for the food industry to sell their waste to the fiber industry.
Tencel and rayon are also good in that they are made out of waste products of other current industries. No extra land is needed! Tencel is specifically made from wood pulp, such as left over from paper manufacturing, and rayon can be made from any cellulosic material.
But what is the advantage of wheat? Sure it is neat that you can made a gluten based fiber (I wonder if people with gluten sensitivities would have skin sensitivities when they wore a garment made of this.), but when there are so many people already hungry in the world it seems almost criminal to be growing food specifically to replace fibers that we can make in a more earth conscious way.
According the article by the ACS the wheat fiber is made from gluten, which as far as I can see means that you would not be left with something normally seen as a food product (though perhaps edible, who knows). This seems like yet another field of science funded by the US government to support Midwestern farmers, similar to the many corn programs.
Now I am definitely not in favor of making these farmers suffer, but it seems like giving incentives to farmers to grow crops that we don't necessarily want just doesn't make sense. Do we want to develop alternative energy sources? Lets talk about incentives for switchgrass rather than corn for ethanol. Do we want to be talking about fiber? I don't think wheat is the answer.