I prefer (programming) web interfaces over graphical interfaces. It is just more portable, platform-independent, and whatnot.
Also I know much more about HTML than about qt, gtk, winforms, or whatever widget set is out there.
Of course, with javascript on the rise, more "powerful" web applications will be created, which will, in turn, bring some of the complexity to the web. However, I think this is not so much a problem because HTML is scalable: you can make do without the "power" of the gui.