By blocking this feature, it is harming the peoples' gaming ability and options at this LAN gaming event. You can't see what other games are being hosted and screaming out across the room "HEY! I'M ABOUT TO HOST A SERIOUS SAM CO-OP SERVER AT IP 172.19.x.x IF ANYONE IS INTERESTED!" would not be welcomed. We are left with having to walk up and down the isles looking for a game we play and when we locate one, ask who is hosting it and what the hoster's IP address IP. Then head back to your system and hope you don't forget the IP address. There are a few games that do not support a direct IP entry, so the only way you can play with others is if you are on the same subnet.
So in the end, yes better equipment would cost more, but thats what sponsors are for. Being able to see what games are being played is a fundamental feature for a LAN party of this size. This must be fixed.