I think the US likes electing actors because actors are better able to appeal to them emotionally, and because their celebrity status makes them appear more trustworthy.

Any successful politician has the traits of a good actor, but actors can claim they're not "really" politicians, even while running for political office, and using the same political tricks as their rivals. It's a weird "Mr. Smith goes to Washington" complex that Americans seem to fall prey to constantly.

Given the nature of the last few Presidential elections in the US, it doesn't seem as if voters want partisan lines crossed, rather, they want those lines maintained and defended with razor wire and snipers.