What makes a great UX? A clean UI, a fast service and possibly no hiccups (to make it very short). The UI has changed a lot from 98 to now (check out web.archive.org) and so did their HTML code. A single line HTML page is obviously a conscious decision and so is the inline CSS.

I don't know you, so I have no idea on your experience in this field, but when you get to deal with I'm not saying huge, but decent amount of users you simply have to deal with scalability under every single aspect. If you don't, chances are you end up delivering a crappy service OR you spend WAY more money (bandwidth, cpu power, etc) than you actually need to.

EDIT: google is obviously more than html and css, and if you really want to have an idea on how they are paranoid with performances you should check out their google app engine documentation.

The primary factor motivating any design over time is inertia. When were these sites started? What was the state of the art then? Who were the people that laid the groundwork for the site?

Google is unique in that A) they can hire top experts in any technology they want, and B) their homepage is extremely minimalistic and easy to change. So to suggest that Google does things out of frustration is just incredibly naive.

You didn't seem to get the point of my original post very well. Allow me to paraphrase a little more bluntly:

* You don't need to be a designer to do awesome things and succeed on the web.

* If you are a web designer and you don't know CSS inside and out, then you are a hack whose skills are already obsolete and sure to become moreso quickly.