Why is it risky to give sudo vim access to ordinary users?

I'd like to create a new user and give him sudo access. To be specific, I want him to use sudo vim and edit httpd.conf. I wrote this in sudoers:

user ALL=(ALL) /usr/bin/vim /etc/httpd/confs/httpd.conf

I, however, heard that this could be risky. Why is this problematic? How serious is the problem?