I agree with you on most of your points, although you have to realise that the Nightly Builds are not really meant for the "mainstream" netgameing audience. The way I understand it, the nightly's are more for testing out cool new stuff like ingame text chat and, as was the case just recently, guided rockets. After the team stabilizes a build enough to release it, they release the latest stable build.
For instance, NATless nightly builds had been around for quite a wile before NATless gameplay was incorporated into the "mainstream" latest stable build. And if you recall, NATless gameplay was quite buggy for a wile before it was stabilized and released.