People saying this have never really spend much time with a modern IDE.
It's like having Vim newbies saying it's too difficult and they prefer Pico, only in this case it's the IDE that's the more advanced.
I'm working on a personal project in my spare time which I can use it on. (Except the project is using Common Lisp so it might not be a good match.)
I forgot to mention in my original post that I've also spent time with Unity3D recently although for some reason I didn't think of it when thinking of IDEs I had used in the past.
Emacs out of the box (install ruby-mode) is not even close to RubyMine. Now, if I spend many hours, and I value my time a great deal, I can get emacs kinda close to the features of intellij.
Frankly, I'd rather pay $60/year than spend many hours trying to get emacs close to as good as RubyMine.
When in Java, there is a mishmash of supporting file types, and it integrates them very well compared to its competitors - jump between .java, .jsp, various .xml for Spring, Hibernate, tag libs, etc etc. If you are "just" programming in a programming language (which is a lost utopia in for J*EE developers), much of this functionality is not of much benefit to you, but you might still find the IDE valuable.
Yes, it's quite good. Visual Studio is also very good in some aspects. And you can also get a lot of mileage out of Eclipse. Also try some Smalltalk environment, you'd be surprised.
The thing is, there are things missing from Vim/Emacs that are not easily added as ad-hoc plugins. Not merely this or that feature: what is mostly missing is a coherence in supporting a specific language.
And once you get ReSharper, also from JetBrains, Visual Studio becomes quite good, too :)
I would hands down pick the right language for a project and then the editor.
(I am actually a Vi guy, but switch to an IDE for any project that involves more than just me)
Emacs + Slime for Common Lisp programming is often held up as an example of this. It provides all the features you mentioned + more. Slime (or rather Swank and alternatives that have been made) has been used for other languages as well: Clojure, JavaScript, Haskell, Ruby, R.
If you work in more than one language then Emacs and Vim quickly start to look enticing since most IDEs either don't support them or don't support them well.
That said, I have no opinion on IntelliJ. I have never used it, but it sure sounds like I should try it out sometime. The last IDE I used was XCode one year ago and Eclipse a couple of years ago and they didn't make me very happy.
edit: My point is, people often hold up both Emacs and Vim as "just text editors" but coupled with a Unix environment and the right programming languages (not Java) they provide a lot of features that IDEs do. Besides that one can use these editors for a lot of other editing tasks like writing manuscripts, e-mail, blogs, etc. giving you the same powerful editing functionality for those tasks.