I'm aware of the ways to force open a new tab, I was just curious as to why this wasn't the default. IMO, it provides for a friendlier user experience.
Opening links in new tabs is trivial (e.g., middle-click). Does every web browser support an equally simple way to force a link to open in the current tab?
(On a related note, a problem I've been having lately is that many JavaScript-heavy sites have links that fail to open when middle-clicked. I wonder whether the people who were previously making unusable Flash sites have moved to JavaScript.)