If people cared about a “working class” background, Rudy Giuliani would be a shoo-in for the presidency. He is the only candidate on both sides who a) has such a background and b) has actually brought about change. Maybe people don´t really want change either?
What counts is not income or upbringing but an appearance of humility, respect for people and the ability to speak their language (which is btw not the same as faking a regional accent).
It is smarter to be positioned as the imperfect servant (remember the great McCain ad?) than the messiah.