I thought about your original question for a while as I reckon I do write them.

On reflection, I think I use the easy ballad tune and style mainly when I write humorous or parody material. I doubt I have written serious material with it. Years ago, I used to sing Ron Angel's "Chemical Worker's Song" unaccompanied, but my material would be comedy or singing traditional verse unaccompanied.

Serious songs of my own I leave to the guitar, as I don't feel just my voice could put over the thought patterns I wish a serious song to portray. (Would help if I could sing better, but there you go....)