It depends on the media that you are using, the audience and the amount of information that you have to display, and the relevance that you want to give.
More a page is cluttered, and less is easy to distinguish in a text a particular word or phrase or in a graphic a specific elements.
I normally make the example of newspapers and adverts in fashion magazines especially when I think about the "audience" factor.
Compare the
The Sun (english tabloid about scandals or petty news)
with a fashion advertise of Channel
The first it is a newspaper, and its target is the common people. They always fill the page as much as possible not leaving much white space available.
Instead Channel targets are the rich people, where you can see that there is no message at all, leaving a lot of white space around the photo,the product and the logo.
Each one of them has a niche that they target, the standard of cheap things it is "clutter how much information is possible (with things like the advertise "save 5.20 pounds" in the sun image), while white-space permits to focus more and give more importance or relevance on subject depending on the amount of white-space around the info/graphic.
Another example quite common are the graphic design & photography books. you can see that white-space is largely used to exalt the graphic that it is showing.
The only people that I ever head that "white space should not be used" were clients that wanted more things in a short amount of space, thinking that white-space it is the equivalent of "empty space", which is not.
As a clean web/graphic designer I love the minimalist approach of the architect Lars von Trier "Less is More" (less design means:more exaltation of the few elements displayed, enhance of aesthetic, more readability).
