Even being inclusive, they've got to draw the line somewhere.
Aw, heck. I've had ships that mounted various types of modified wands on them, since 1E. It gives a darn good reason for including wizards in the crew of a warship.Gunpowder-based artillery on ships for naval battles - hells yeah!
My problem is that I can't think of a way to allow the last one without logically having to allow at least one of the other three.
Over 100 responses votes yielding less than 5% yes votes. Seems like gunslinger is unwelcome to the core rules.
While you may be downplaying the "maybe" part...You are downplaying how thoroughly the "maybe in a later splat book" option is thrashing both the yes and no options.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.