All X servers need to be run as root in order to get direct access to your video hardware. Older versions of XFree86 (<= 3.3.6) installed all bundled servers to be automatically run as root (setuid to root). This is obviously a security hazard because X servers are large, complicated programs. Newer versions of XFree86 do not install the servers setuid to root for just this reason.
Obviously, running an X server as the root user is not acceptable, nor a good idea security-wise. There are two ways to be able to use X as a regular user. The first is to use xdm or another display manager (e.g., kdm); the second is to use the Xwrapper.
xdm is a daemon that handles graphical logins. It is usually started at boot time, and is responsible for authenticating users and starting their sessions; it is essentially the graphical counterpart of getty(8) and login(1). For more information on xdm see the XFree86 documentation, and the the FAQ entry on it.
Xwrapper is the X server wrapper; it is a small utility to enable one to manually run an X server while maintaining reasonable safety. It performs some sanity checks on the command line arguments given, and if they pass, runs the appropriate X server. If you do not want to run a display manger for whatever reason, this is for you. If you have installed the complete ports collection, you can find the port in /usr/ports/x11/wrapper.