One reason for the seeming preponderance of lefty folkies is that many songs are often about causes and about change. They're about taking the piss out of governments and the ruling class. They're about the human condition and tell stories about horrible things that have happened to 'have nots' at the hands of the 'haves'.

Conservatives, by definition, don't want change and they usually support whoever's in charge unless that person wants to change things or take something away from the 'haves' and give it to the 'have nots'. There aren't a whole lot of songs about "we're alright, Jack and we don't give a hamster's heinie about YOU." The 'haves' don't write songs. They pretty much do what they've always done: play "hear no evil, see no evil, sing no evil" and ignore those who are dissatisfied or actively tell them to shut up.