I've seen a few people saying that, but honestly, I don't see why it would be a suicide. I don't really care that an application can change my port forwarding configuration. Why would I?
If someone can open ports in your router it can led to all kind of security holes. There was even a bug in the windows implementation of upnp that allowed anyone in the internet to open a port in your router. Its just not safe to allow automatically opening ports in your router.