While waishengren really control the politics and military, you musn't forget that after the lifting of martial law the most prominent bensheng politicians are all Hakka (LTH, CSB, AL ...). The Hokkiens may be boisterous, crude and gangsterish, but it's the Hakka's cuning, shrewdness, calculativeness and ruthlessness that make them dominate the political scene in east Asia.
Havg said that, Hokkiens form the largest electoral base in Taiwan, and in a democracy that cannot be ignored. But what's holdg them back is the perennial desire for reunification (waisheng) and the pull of a common Chinese culture (benshengren) from my conversations with Taiwanese. Hence status quo
Hakka leaders, Hokkien masses ... Taiwan in many ways similar to Singapore. But they have way more balls.