Sometimes port forwarding is needed no matter how well designed your network and equipment are. For example, I have three and sometimes four VoIP adapters operating behind my router (plus soft phones), and some of them are reached directly -- i.e., without using proxies. There would be no way a call could reach myadapter@mypublicipaddressort without forwarding that particular port to my adapter.

Edit: the smiley should be a colon and a "p."