Dueukrag — It is more complex than it sounds. Your aircraft have to be specifically designed for the stress. The catapult system has to provide a reliable force/speed on each launch. A failure means a lost multi million dollar (F/A-18 approx $30 million US) aircraft. It may not be that complex in each small part, but there is no room for error.
On the article, spot on that the worry is not on their aircraft carrier under construction. The worry is on the unsinkable ones they are building in the South China Sea. Those aircraft carriers they are building can’t launch fully fueled and armed aircraft. Those islands can, and they have a lot more defensive capability.