It opens the door for potential stupidity, and there are plenty of those who will take advantage when given the chance. Things have worked quite well as-is, would like to keep it that way.
I guess we disagree here. The potential is higher, but in practice, "incidents" will be less. And there are a lot of studies that support this. And in fact a good example of this is the Reet Retreat channel. I think that is still open to anyone? I don't know for sure, but I haven't seen any incidents about it. In contrast, I do recognize that it's hard to measure the success of opening that channel up and it could be a net-zero change. Another example is the Budabot project. Google code doesn't give me the option to allow commits from anyone, but I am very open to giving write access to the svn repo. Of course I do monitor the commits and I can revert a commit if necessary but I have never had to revert a change due to a malicious commit that someone has made. I believe that I never will. But more importantly than that I haven't had any bad commits, I have had some really great commits and I can definitely see the effect that this has in the way of bugs fixed and features added.
If I was you, I would open up the whole bot, I'd let anyone create channels, and then let the owners of the channels set permissions on them if they wanted.
Given that there are about 550 people on during prime time and 250-300 otherwise [per server], there are still a lot of people that you could get on AOSpeak, and I think opening the server up would help that.