It's the lack of layers that I find most appealing, to be honest. Kind of like the difference between Graham Greene (who just tells the story, and lets you fill in the complexities of motivation for yourself) and Thomas Hardy, who is forever poking his head through the narrative and telling you what it all means.

This means that -- even though some of them are long -- a lot of ballads move along at a cracking pace*. Some of them are almost cinematic in the way they shift from one scene to another, or even flash forward to key stages in the story. Think of,

At the age of sixteen, he was a married man,
At the age of seventeen, he was the father of a son,
At the age of eighteen, his grave was growing green,

for instance.

* Lord Randall excepted, of course. Why didn't they just shoot him? ;-)