Why didn't Henry Ford put automatic transmissions and GPS navigation into his first Model A cars? Innovation usually follows a path where 1) new technology makes new things possible and 2) in time users learn more and more about what might be useful.
Why didn't they make a multi-panel gold-plated mirror telescope shot into space in the 1600s? The answer is obvious. Gradually telescopes have been improved on the ground, then on mountain tops, and now in space. The James Webb is only one of them, since 1970 there have been more than 90 different telescopes of all kinds of capabilities placed operational in space.
So what makes the James Webb so special? Its mirror is large, it is coated with a thin layer of gold and its detectors are cooled almost to absolute zero, which allows the Webb to gather light into the infrared region. That is important for several reasons. We know space is expanding and the most distant stars and galaxies are traveling away from Earth at high speeds. This causes what is called a "red shift" so light that would otherwise have been visible light now shows up as infrared. Without Webb's capability we could not see them. Also as stars and galaxies cool and emit more light in the longer regions (red and infrared) the Webb can get a better look at them.
This program is titled "ultimate space telescope" and I add "so far", because it is reasonable to believe that new knowledge about the universe will lead us to build something yet bigger and more capable. All the while knowing that we can never actually travel to any of those far-away places.
Good program, the James Webb has been operational for only a few months and has generated vast amounts of observational data. Going forward a big part of the challenge will be to have enough astrophysicists and astronomy students to examine and interpret all the data.
