David Frum says that there was a disconnect between Huntsman's personality and his program:
Huntsman offered a critique of what has gone wrong in the modern Republican party: too anti-science, too socially conservative, too militarily interventionist, too hostile to expertise.
He did not however offer a unique selling proposition for his own candidacy. Even supposing a Republican primary voter agreed with every point in Huntsman's critique (and surprisingly many do agree)—what then? Huntsman's answer to the party's problems was himself: smart, sophisticated, worldly, pragmatic. But every one of those characteristics is shared with Romney. What Huntsman did not offer was a programmatic alternative. On the contrary, the Huntsman program doubled down on Norquistism: big tax cuts, Ryan plan, etc.
This program created a contrast with Romney, but in the wrong direction: the least ideological Republican candidate now offered the most ideological economic platform. Ace instead focuses on how Huntsman seemed to treat the base:
It's difficult to like someone who clearly doesn't like you. While in the past several weeks conservatives, seeking some alternative to Romney, have started to at least entertain the possibility of backing Huntsman, it was all but impossible given Huntsman's frequent obnoxious signaling that he just doesn't like us.
It's not just an emotional thing, either. If a candidate specifically lays down the marker that he doesn't think much of our opinion but cares a great deal about what the editors of Vogue might think, that's a pretty strong sign that he'd govern in such a way to pander to their opinions and against ours.