At pywikipedia, and more generally in the bot communities on each projects, we have regularly young power-users showing up, and trying out bots, because, well... mostly e-fame I would say, and the excitement of playing with a new toy. Depending on the bot policies, those rather Python-unskilled people can get bot flags on some wikis, and end up running tools they dont understand and that they dont update. That hurts, in many contexts.
This remark is spot on. I'm an admin on dewikinews and we had all this trouble in the past. One bot operator even had the boldness to tell us he can't fix his misbehaving bot because he just uses pywikipedia and don't know how to modify it.
Of course i can't speak for dewikinews in whole, but i believe that the existence of a central iw-bot would be enough reason to disallow all other iw-bots and this would really change things to the better. To be frank, i'm soooo sick of all this iw-bot madness.
Regards, Michael