John, although you apparently already gave up on the idea, I believe the `visually very unappealing` kind of problem is not solved by removing the ability to create headings, but simply by changing the CSS template or the HTML generator settings of this site to produce a less obtrusive heading look. 

Currently the site defaults for using `<h2>` for
<h2>Headings</h2>
created by a "markdown underline" `-----` under the text, although manual formatting using HTML tags also allows for less obtrusive `<h3>`
<h3> Headings </h3>
already - it's just that a lot of people (including myself) either do not take the trouble to use HTML tags or do not know about them. Maybe `<h3>` should simply be made the default for markdown-created headlines since the overly large font along with the huge spacings (*font-size:140%;margin-bottom:7px;line-height:1.3*) indeed break the flow of text a whole bit too much.