There is one key misunderstanding. You assume people will come to your archive from the archive front door. The reality is they more often hit your threads directly. Your threads has the content they are searching, and they just click "reply" trying to get in. They probably never see the front door, or even if they see, their focus is the thread, so they probably will miss your notice.
I understand your need for simplicity. The good news is that you can get it from Nabble. In about a week's time, we will release the mailing list feature. So, your archive can also function as a fully featured mailing list.
The root of the trouble is not this or that little features. The root of the trouble is the mailing list software doesn't have a good archive. Yahoo sucks. Googlegroup is better. But I am confident Nabble will beat everything out there.
So bear with us for another week, possibly even shorter, and check out our mailing list feature. Then we chat again.