No one can force you to learn vi, just as no one can force you to do backups. However, in my opinion, doing both will make you a better administrator. There will come a time when having done regular backups will save your career. There may also come a time when knowing vi will save you the embarrassment of having to tell your client or boss that you can’t accomplish a task because you need to edit a file and the only editor is the system default: vi.
On the other hand it is my favorite editor. In fact, for many years most of my writing was done using vi. That included both books and articles. I find it a lot easier than using a so-called wysiwyg editor as I generally don’t care what the text is going to look like as my editors are going to change the appearance anyway. Therefore, whether I am writing on Linux, Solaris, or even Windows, I have the same, familiar editor.
Then there is the fact that the files edited with vi are portable to any word processor, regardless of the operating system. Plus it makes making global changes a whole lot easier.