If for some reason I get a plugin removed form the Plugins folder, Ai wipes the entire tool panel which had the tool associated with the removed plugin.

Even worse — when a plugin is returned back to the folder, Ai won’t restore the panel! It stays completely broken and empty. Each next launch Ai seemingly restores it, but the next launch it’s empty again. Resaving the panel does not help.

So you have to rely on backups — manual backups, because, again, Ai fails at properly backing up these automatically.