I agree with you, I still do not use liquid layouts often for the reasons you mention... yet some people do a very good job of making very nice liquid layouts. It probably takes some mastering...
One thing that makes them so useful is the increasing number of people who have "big screens". Most of us designers still have to take into consideration those remaining 15 inches screen (in France, something like 14 to 15% of the market). On a 17 or 19 inches screen, or even on wide screen laptops, it’s a great loss of space....
About the content being thrown off by resizing, as explained on the articles you can set max-width for content (but not all browsers understand it...).
It makes more sense taking the viewport as reference point. Yet it makes thing sometimes hard to figure out when designing... not to mention, as you say, those unnerving cross browser compatibility issue... Sadly, the upcoming IE7 won’t help that much solving the "IE factor"...
There is still many things preventing the web to be at its "full potential", first of which Internet Explorer. I mean when you see what CSS3 has to offer, you first drool at the prospect and second you start wondering if IE will support those in 2010 (IE7 won’t even support CSS2 fully

).
Why oh why is M$ bothering us... and why oh why people don’t switch browsers and drop IE...