This question has come up in the past, so let me first explain why links don't open in new tabs by default. There are two main reasons. First, there is a very easy way to open links in new tabs, which is "cmd-click" (Mac) or "shift-click" (Windows).
Second, once I force links to open in a new tab there is no way for a user to NOT have that happen. In the current setup one has to remember the special click to get a new tab, but at least it is a choice.
Regarding your actual question -- whether there can be a setting for this -- that is something we have considered in the past. The problem is that every setting adds complexity and often people change settings and later forget that they ever did so. There is also the issue that it would add some level of performance overhead.
The compromise that we have adopted is to make certain types of links always open new tabs, like the entries in one of Angie's list posts, or the product pictures in a post.
