The cynical explanation is that Bill stole their issues - after welfare reform, they were denied their standard racist tales of welfare queens. He balanced the budget that they put out of whack - and she may repeat the trick. But there's also something to the cultural explanation - to trad vals types, they're the incarnation of the 60s and despise them for it.
[WS:] I think the cultural explanation is the main reason - America is still a nation of petit bourgeois, provincial philistines with profoundly anti-intellectual orientation, and for whom attacking "liberal elites" is the most favorite blood sport. Perhaps the number of these philistines fell down somewhat since the times of Mark Twain, HL Mencken or Lewis Sinclair, but they represent the dominant chunk of society, both numerically and culturally, so every politician must bow to them to stay afloat (as demonstrated by the political misfortunes of Gore and Kerry who lost to the philistine Bush).
Hillary is the quintessential "liberal elite" and embodiment of their values - so she is viscerally hated by these philistines, no matter how business friendly she might be.
Wojtek