We deal with this in web development all the time. Programmers are very smart folks mostly. They can do wonderful things with code that plumbers and doctors either can't or don't want to do. But plumbers and doctors of course help you in return with what they provide. It's the same for the art side web design and web site usability - many programmers create something complex yet fail to make it easy or useful for others. They'll even get offended when you suggest things like a Home button, because for them a home button is superfluous.
It's relatively simple for anyone these days to "make a web site", especially people who work in science or math fields, backend code, that kind of thing. But what we see time and time again is that programmers and folks in the "thinking" (left brain) type of fields have trouble with design/usability. Design and usability issues often lean toward the arts; the "intuitive" (right brain) fields.
While we're all different of course, and have our strengths and weaknesses, generally artists don't make complex web sites and programmers don't make very pretty or easy-to-use ones. It's just left/right brain normal issues. That's why web development firms are often made up of at least a programmer, an artist and a project manager. It's rare to find one person who handles all that competently.
It's often just a matter of a left brain person that understands a web site is "good enough" if it can perform the complex task goals they have. Design and such is left for later, and often "later" doesn't roll around until enough people have said "gee, a home button would be nice".
I think Gox and Tradehill are both pretty weak offerings as far as design/usability but that's IMO. There's always the Google argument though. Can't get more spartan than that and I find a bunch of Google's tools not all that user-friendly. I still have trouble finding the button to compose a new email in Gmail and I've been using it for years. And yet, as bad as the design/usability of Google (+tools) is, one can't argue with its success.