I think that /etc/openvpn directory's 755 permission bits are default for many distributions including maemo.org's openvpn package (if it hasn't changed), but I can understand your view.

Problem with openvpn applet is that is is running inside hildon-desktop and it is always running as user. Applet needs to be able to read the configuration file and directory listing of /etc/openvpn, but it doesn't need to be able to read certificates or keys. For importing files and starting openvpn process it uses sudo.