Looking at the source code for Stack Overflow, I noticed they have used tables and inline CSS quite a bit, also something I found odd was use of inline table attribute forma
"css is too hard" and "tables are quicker and easier" excuses, coupled with some down right misgivings about what's wrong with the use of tables for structural markup.
The question is asking why SO chose to use tables, inline css, etc., to which I think the answer is probably nothing more than that either they aren't familiar with graceful degradation and semantics, or they didn't consider it important enough to devote the time and resources.
There's nothing wrong with not knowing css, but to dismiss semantic markup and the proper use of css just because you don't know it is just WRONG.
To champion that your site looks the same in every browser using tables, while not giving a seconds thought to those that don't use a visual browser smacks of selfishness - that's a strong word, and I apologize for the tone, as I don't intend to insult.
BTW - I take umbrage at the idea that the use of tables for structural markup is a 'holy war'. While some might think that Semantic markup is overly championed, it is not based upon blind faith.
Tables are not evil, but certain uses of them (which used to be everywhere) are evil. Namely, using spacers, nested cells, etc, to control margin and padding.
Even though everyone now a days talk about layout with css and divs, the truth of the matter is css is awful when it comes to layout. You can only do so much. Look at some suggested solutions to get 2 or 3 column layouts using css, they all suck. Throwing a <table><tr><td id="left-column"><td id="right-column"></tr></table>
is a lot easier.
css is just not suitable for non-trivial layout (and by that, I mean pure div/css)
The table solution I just threw above needs to use css to control width and padding and borders and background images, etc.
Tables and layout
SO's layout is not based on tables.
At a quick glance, I'd say SO layout is 80% div-based and 20% table-based. Tables are used in the header and on the "badges" box. Table use is appropriate for badges IMHO (it's a list of items, after all), not so good for the header.
Anywhere else, divs are used.
Inline CSS
Again, many inline definitions are used (probably to quickly mockup site's structure), but SO correctly uses also css (to style the divs and to provide print formatting).
IE8 will be the last major browser to finally add support for the CSS display: table-* values, so the distinction will go away. Hopefully this will end the whining about how hard CSS is, and people can stop polluting markup with presentation.
Give up and use tables
I have no idea, but the only explanation I can come up with is that Jeff isn't as supportive of web standards as he'd like us to think and none of the team are that hot on CSS. Programmers often use cross-browser-ness, ease-of-use and numerous other supposed time benefits to excuse their lack of CSS skills. And I don't mean that as a criticism, they're probably really good at programming C#/Java/Ruby/SQL/whatever, they just can't seem to admit that they don't really know something as well us a bunch of polo-neck wearing, Mac Book wielding designers...