For example it can track the time it takes to work on a task and it can easily hide/show descriptions. So it goes beyond simple text editing. Of course, I believe it has been ported to other text editors. At least I know there is a port for Sublime Text, but it's incomplete and much less capable. Vim probably has a port too, but then if you end up customizing Vim, you might want to take a look at Emacs :-)
CTags is a pain, since you have to reindex your files periodically and it doesn't work well for other people's libraries. In IntelliJ IDEA it simply works, you can just click on a class / function definition and if it doesn't have the sources available for that JAR (say it's a library you depend on), it downloads those sources automatically and takes you to the definition. For Emacs it works if you have the right plugin installed - works for Clojure and for Scala / Java for example (though for Scala / Java, we are talking about an Eclipse-based engine running in the background :))
I do get the mentality of Vim users, I've been there and I even use Vim sometimes, but depending on the problems you're working on and the platform you're using, I lean towards the IDE approach nowadays. And Emacs is like a general purpose and non-bloated IDE.