I use IntelliJ for all my coding at this point, but I still find I need to keep a copy of jEdit or another editor around to edit random files. While I can open any file in IntelliJ, the editor is really project-based, and doesn't make it easy or comfortable for me to work with files outside of my project.
The way I see it, IntelliJ belongs to a class of tools that are project-based, where the developer's focus is on a set of files that belong (usually) to one top-level directory. Within that structure, the editor has good knowledge of how the files relate to the project and to each other.
jEdit on the other hand, is basically a super-text editor, which, for files matching some pattern (name pattern, for example), it can provide syntax highlighting, plugin support, etc. I find I can't get 100% of my job done--or anywhere close--if I don't have a regular text editor at hand.
IntelliJ seems to already have most of the functionality one would want, however, it would need to be organized somewhat differently. For example, in jEdit, settings for the buffer can be per-buffer or per "file type" (where file type may be based on a name match, for example). We already have good search functionality and there is at least one "file browser" plugin. Some features are missing, for example decent scripting support.
Question is--does JetBrains have any interest in expanding the scope of what IntelliJ is aimed to support to include this use-case?
The thing is, whether we're interested or not, we will have to support a file-based mode of operation anyway. It's a major requirement for scripting languages, and also to a large degree for Web development. So, yes, the next release of IntelliJ IDEA will be much better suited to such mode of operation.