... A more realistic problem is I actually _might_ want people to automatically send traffic to my comments function if someone eventually builds an application to forward requests to my page to make it easier for my users. Again, you could argue that in that case I should explicitly allow that one referrer in, and I might agree, but wow... this is seeming like an administration nightmare, even on a small site like mine.
If you change your policy on who should and shouldn't be sending requests to certain pages, you should expect that you will need to do some work to make that policy take affect. That's true no matter what kind of enforcement mechanism you are using. The more elaborate your policy, the more work you are going to have to do to describe it.
Is the extra work required to enable the policy worth the trouble? It depends on the site.
Regards, Brian