Again, the whole idea is to keep the casual person off your network, which WEP will do. If someone has the resources and inclination, they will get into your network, regardless of how it's secured.
Disabling SSID broadcast, MAC address reservation and WEP are only deterents. However, compared to the number of open networks still out there, it might be enough to keep prying eyes off yours. An open target will always be more desirable than a secured one, even if the security is flawed.