For me, one of the main reasons for using a VCS is to avoid cluttering my working directory with lots of mainly useless files with cryptic filenames like:
With such a system, it is hard to keep track of which changes occurred in which version. It gets worse if you have multiple authors collaborating on a document with different file naming conventions. It gets even worse if you are using a similar system for your bibtex and image files, as you have to keep remembering to update the references to the files in the main document. It gets even more worse if you are collaborating via sending email attachments and don't know for sure that you have saved every single version that was emailed into your working directory.
With a VCS you just have one copy of each file, so you have a much cleaner and easier to navigate working directory. The VCS should make it easy for you to find out where changes were made, so that you can easily find things when you want to restore something that you previously edited out. Since the VCS stores everything, you know that every version of the file is available in one place. It should also declutter your email inbox a little bit as you won't need the attachments and emails that just announce updates to the document are no longer needed.