Why bundle version a control plugin with an IDE?

Integration of the IDE with version control and, in particular, software change management (SCM) helps bringing together the philosophies of the IDE and the source control system.

One example is temporary files and binaries, that should not be checked-in and, e.g. in Visual Studio, end up within the source directory if you're not carefully creating new project and solution templates with a non-default directory configuration.

Another could be tracking of work items and complex bug fixes.

Also it saves some ceremony and context-switching when editing files.

Advanced integrations may also allow to push the change management system's concept of "configuration" ("branch", "tag", "view") into the IDE.

ClearCase integration, however, is clearly not "advanced".

I like how some IDE's implement this. Ankh-SVN for Visual Studio is not that great and is a bit buggy, however Subeclipse I find to work exceedingly well when I'm using Eclipse.

I think it really depends on the IDE you're using and the quality of that plug-in. It's going to work well for some setups and terrible for others.

That's why I like Subversion with Tortoise SVN so much. I can choose to use the IDE integration when and where it makes sense, otherwise, just like you said, I can simply use the command line or in my case, the windows explorer based client!

Integrated Source Control also helps to only keep the important files under Source control. For example, when I add a new File in Visual Studio, the Plugin (visualSVN) will allow me to add it easily without me having to remember to go outside of my IDE and run the command to add it to the repository. On the other hand, it will automatically ignore temporary files, like the obj/ and bin/ Folders.

Essentially: Integrated Version Control that actually works is a great way to keep the repository clean and complete.

A lot of it is simply the preference and comfort level of the user. Some folks are comfortable with the command line. Some prefer a GUI.

I wouldn't make generalized assumptions that all version control within the IDE is bad or buggy based on experiences with a particular plugin which had issues.