So the idea is quite simple. Make it so that a plugin can be updated by others too. Why? Because there are some plugins that are just too awesome to stay inactive. (@aliuly is no longer active, but his plugins are very nice) Or some plugins need to be updated (String -> StringTag), but the plugin author is inactive. I am not sure how this could be done on XenForo though; maybe you still can submit as if it was a new plugin, but it will be put under that plugin as an update.
What if someone submits an update that completely changes the way the author has done something and if reversed, will cause issues? There are a list of problems that would arise if this feature was added although, you can also see some of the benefits that it would bring.
Good point, but I expect these plugins also being inspected by the plugin reviewers and writing the plugin completely differently can be considered as an complete re-write update, unless it breaks, but these will be rejected by the reviewers. Oops... forgot to add that.
For outdated plugins (<= Alpha_1.3): You don't need permission. As long as you don't have the same plugin name (to avoid confusion), you can create a new plugin with the exactly same features as the outdated plugin. This is because you simply can't copy it at all, except the idea -- they are totally different. And you do not need permission for the idea if the idea isn't original. Only very few plugins, e.g. NumericRanks, are original ideas. For these plugins, you may politely acknowledge the original author first. And it is your own moral judgement whether you should continue creating another plugin using their idea, without their explicit approval, or even with their objection. (Look at Minecraft and SurvivalCraft; there is definitely nothing technically offensive stealing/copying/"referencing" ideas) For outdated plugins (Alpha_1.4+): If the original author has been inactive for more than, like, 6 months, and you only need to slightly edit the plugin to make it work with new API versions (especially API 1.x.x -> 2.x.x), maybe the PocketMine staff should create a new forum called "Plugin Updates", where people can submit edited versions of the plugins and staff members can review the changes and update the plugins if approved. For plugins that do work and you found them on GitHub: You shouldn't submit them without their permission. They may be still W.I.P., or maybe the author doesn't want to submit them yet, or maybe the author already submitted them but they are waiting for approval/rejected for various reasons. You should ask for their explicit permission first.
