Oven Costs played a huge role
Building ovens the size of small houses to fit
the low selling volume of kayaks via rotational molds
became prohibitively costly for many manufacturers.
Induction heating a sheet of plastic in a holding frame
to make a top/bottom of a kayak is much, much cheaper,
and increased profits.
It also eliminated the need for drying the pellets
and time=money in manufacturing.
http://www.ptonline.com/columns/you-must-dry-hygroscopic-resins
Two main reasons many switched forming operations
yes - there ARE orphan pellets!
They sweep them up off the floor and use them for those multicolored poly kayaks!
Sort of like how General Mills makes Chex Mix.