>But why HTML at all? What can HTML do that SVG can't already do or won't very soon be able to do?
scrolling divisions with as much text in them as you want, layout determined by how much content you have in a particular area(this is different from layout determined by percentage). A text element with a bunch of tspan child elements  does not seem to me to provide a good way of presenting document information, and is at any rate not particularly suitable to transformation from many document formats which do not care how much space the text takes up.

In short better, if better is taken to mean less worrisome, text layout.