My personal opinion is that the Pioneer Plasmas cost considerably more, but the PQ was not that much better than rivals (Samsung, Panasonic, Sony) at least in my opinion. I can't help but think the higher cost for their units is what hurts the sales (it certainly kept me from buying one).
Subjectively, I do think Plasma sets offer better PQ, but in the end it comes down to profitablility. If it costs less to make a product that sells then that is the product that will be made.