In 23th century (Star Trek universe), CRT dislays was still curved, instead of flat screen :
I wonder why they didin't used special effects, very simple one needed here, instead of a CRT TV screen, for these scene.
LED get head, and so reduced efficience, whichgenerates more heat... So if we had Global Warming LEDs will shine less. Well, this could be a add against Global Warming.
The new LEDs use a different material, a combination, that have high efficience and it's also cheaper. Besides that, the princeple are the same, I guess.