Except for the fact that they're really heavy, use a lot of power and don't work very well if you've got windows in the room. I understand why they may still be a legitimate choice for cinephiles, but for the average family room LCD makes a lot more sense.
I don't think they're that heavy, and the energy thing has improved as well
As far as light, I absolutely agree on that though. Slipped my mind before, but makes sense.
But plasma often does offer superior quality for the cost to alternatives, and I would think that counts for something