Too expensive, chunky, and power hungry while LCDs kept getting cheaper and better.
This is an important point. My household uses very little power and when we eventually switched out our old plasma TV after a decade or so of use, our power bill halved. It's hard to pin it all on the TV because this is hardly a scientific experiment but that was the only notable change during that period.
(EU electricity prices. With increasing prices expected it is probably going to take less than originally estimated.)
It disturbs me how millions of plasma TVs would have been made. Now they are unwanted with nowhere to go. I like to imagine a highly efficient recycle program would strip them down for parts. In reality I suspect most end up in landfill and aren't much value in the recycle business.