Since version 7.4.2111 we load a less conservative defaults.vim file if ~/.vimrc is not found. These options can not be overwritten from global /etc/vimrc.
For example the new defaults enable mouse integration. To disable mouse integration I have to create ~/.vimrc for every user. I can not disable mouse integration from /etc/vimrc.

IMHO /etc/vimrc should have precedence to the default settings.