Balsa kits are rapidly becoming an elitist branch of the hobby/Art because of the cost of the actual raw material. When you add the problems of warping and splitting of the balsa, post kit manufacture, the problems for the manufacturers multiply.
I love Balsa and have a number of models myself, mostly scratch built, they do seem to suffer more than their share of "Hangar Rash". Recently I did an exercise of weight reduction of a FB plane by removing paper and using Balsa to reinforce the bare foam with some success.
Psyborg is correct in his assertion of the business model under which FT operates, and in FT's position I would not wish to invest in a fading, (not fatally though), expensive technology which is not easily utilised by entry level RC users or builders and also would be slow moving off the shelf. For what you get for your dollar FB is hard to beat.
Should you wish to build the Pietenpol in Balsa I am sure that there are enough "Balsa Nerds", (myself included), who would gladly provide guidance through the procedure if you require it.