Quitting a server with a message to connect to another one, however, is a use case that I think probably applies to... 5% of cases? Maybe I'm overexaggerating.
Not really, I'm sure there's more than 5% who would like to be able quit and actually have a quit message without using the above in 2 commands.
The point here is that if mIRC were to have a switch to execute some vaguely relevant command for every other command, we would have hundreds of switches littering every command-- and then, when mIRC has a *valid* reason to add a switch, the letter code that best suits it would be taken, complicating the interface.
Well, there 52 switches (a-z A-Z) that can be used, and even then I doubt all 52 will be used, it's a possibility but not likely.
Maybe in the future, /server -q will stand for "quiet" and hide the *** Notices and MOTD? I think that would be a better meaning for "-q", personally. (this is not a suggestion)
And -q was an example, could be anything.