Granted, all the "automatic" part messages I've seen are 99% of the time spam, annoying ascii art, blinding colours and frankly 'automatic' (meaning they have no relevance to the conversation at hand) - many bots/scripts use the part message to relay information to a channel (why its parting etc.) without having to send two lines to the server. Obviously this has nothing to do with a 'default' part message for when we part a channel by closing the window, however I feel it shows part messages aren't useless when used appropriately.
Given many IRCds have modes to squelch part messages, scripts can be written to filter part messages, and this functionality already exists in a kludge, shouldn't users be given the option to specify a default part message? Maybe it could be written in so it will override any on *:part messages too (ie: it will trigger first), as I'm sure many script users don't want to be walking billboards for their scripts author, just as we don't like reading said spam.
