First:
Good design and functionality are the same thing. The saying goes form over function, not design over function. If one thing functions better than another, it can be described as better design.

I'd bet dollars to doughnuts that some of the simpler proposed UI changes (better visual separation, bigger fonts, clearer visual distinction of elements, good-sized clickable iconic images) would improve the Zappos site tremendously.

Second:
Most of the posts on this page are good examples of what kills me working as a web guy.

Engineers/Analysts want everything down to the color of each link to be data driven, to the point of irrationality. To me it's obvious when a design has been manhandled by this division of a Web team. Not all points of data are meaningful, and data does not know all ("Yes, it’s true that a team at Google couldn’t decide between two blues, so they’re testing 41 shades between each blue to see which one performs better. I had a recent debate over whether a border should be 3, 4 or 5 pixels wide, and was asked to prove my case." http://stopdesign.com/archive/2009/03/20/goodbye-google.html)

Developers don't grasp every detail of what good design should be and tend to simplify and marginalize the web designer job. (Although seeing a lot of the "talent" out there, I can understand why this happens a lot. Great web designers are rare, hold on to them tightly)

Designers have a hell of a time describing why their abstract ideas have practical implications. At the same time a lot of designers grow strong opinions and giant egos. It practically comes with the job description. If a designer can't fight for their ideas well enough (most of which being abstract), the get to eat other peoples ideas all day long. Typicaly the ideas of people that have no background in design T_T

There's a balance to this. I know it's out there, and I know it can work. All of these positions are valuable, and they all have their areas of expertise. Why the hell do conversations like this turn into food fights between the Jets, the Sharks and the Goths (ok that metaphor doesn't scale)

Lastly, here's my two cents
As a first time viewer of their current site I find the layout of the site confusing. The site seems to have a hard time pulling my attention to any one spot that I care about.

Banner blindness is in full effect on the homepage.
The dual sidebar design with all text links seems like a bad choice to me. I didn't start caring about anything until I reached the box with highlighted products with pictures of shoes... But they weren't shoes I cared about since the site knows nothing about me.

The current site is a large chorus of voices all talking at the same volume. However web sites should not be a high school choir, there should be points of interest that stick out for me to sink my teeth into.

Granted, if I realy want shoes from them, it wouldn't be hard to read through their links to find what I want. But the design could make this choice easier and quicker (IMO).

So the gradient love may not be the road to go, that would depend on the audience (although I happen to enjoy a lot of it). Yes this UI is totally possible (even in IE6 gasp) in the hands of a compotent HTML CSS dev, but I imagine there are stricter bandwidth constraints due to the amount of traffic they get.

His IA may not be the right one, but that's why baby Jesus made A>B & multi-variant testing. It's the job of an engineer or analyst to tell the designer where things should go and about how large they should be. He correctly points out a lot of areas that the design is lacking.

This isn't to say Andrew's is the holy grail, but I think it's an interesting stab at quite a few (what I see as) problems.