No it shouldn't. The intended way to set it up is with 2 network cards. I see no need at all to change the installer merely because the proper setup doesn't suit a few people that are only interested in half the features.
The promotional videos all make it sound like one can easily take advantage of all sorts of extra hardware if they happen to have it, but if they don't have it LinuxMCE will fallback gracefully with as much functionality as possible given the circumstances. I don't have two NICs, nor do I have any great intention of running a second drop to the living room. (I'm running a combined front/backend, which is a recommended configuration.) My choice is either to add a wireless link to the local network (so now I'll be quite bandwidth limited as far as stream to my other machines), run an unsightly cable across the floor and around the house, or go through the hassle of running a second cable through the walls. Nice.