IMO, Pioneer just didn't get their business model right. Given the huge gap in market share versus Panasonic, maybe they should have lowered their prices so that they could capture market share and build up scale over time which should have lowered their production costs. Also, in terms of brand recognition, I think the Panasonic brand is more recognisable to the "average consumer". Panasonic has done a good job in advertising their brand and marketing their product specs well which can quite easily convince an average consumer to buy Panasonic over Pioneer.
If not for specialist reviews from magazines like What Hi-Fi, I might not have even considered a Pioneer as the brand recognition and in store promotion of the other brands like Sony, Samsung, Panasonic, Sharp, etc... are too strong to ignore.