As a fellow Chinese, I can actually explain why. Yao Ming came from the home country of China, and during the time Yao was in the NBA, he was pretty much representing the Asian race of the NBA.
The Jeremy Lin "cult" following is through two streams of fans:
1. The Asian-American fanboys who are avid basketball fans and idolizing Jeremy Lin and looking to Jeremy Lin as a role model to follow.
2. Taiwanese people - mainly through a political separation... Jeremy Lin has stated many times to the media that he was Chinese, but emphasized his Taiwanese ethnicity numerous times. If you are unaware, there's always been a discourse between China and Taiwan, more importantly Taiwan's heritage stemming from China. However, Taiwanese people tend to have a big ego and tout Jeremy Lin as a Taiwanese NBA player rather than Asian. Essentially it's almost using Lin as a political crutch to show China that Taiwan is better.