The loopback network device isn't active by default during kickstart installations. It can be activated easily enough by doing "ifconfig lo up" in the %pre script of the ks.cfg file, but there's no reason why it shouldn't be activated by default. Leaving it down can prevent stuff from working, e.g., during our kickstart we install and start the postgresql server and then try to connect to it on 127.0.0.1.
It definitely should be getting brought up via the initLoopback function in loader2/net.c. Can you boot with loglevel=debug and attach the logs to this bug report? Maybe there's something odd going on here.