Thor's nuts, I am sick and tired of "appendix N" being an argument for anything.
I am nearly 40 years old. Of the authors listed in appendix N, I recognize six names, and of those six authors, I have only actually read anything written by two of them (Lovecraft and Tolkien). Howard, Moorcock, and Vance I only recognize explicitly because of discussions about TTRPGs, while Burroughs I've had exposure to elsewise.
I have at least one player in my current D&D 5e game that has never heard of Vance before joining my table, and that was because I had to explain to him what I meant by the phrase "Vancian casting."
I have never read a Conan story. I'm never going to read a Conan story. If D&D wants to continue to insist that it is designed for characters and narratives I've only ever heard about second-hand from nearly a century ago, I don't see why anyone born in 
this century would be interested in it.
	
		
	
	
		
		
			Because if they're simple weapons they interact with Monk and Rogue in bizarre ways
		
		
	 
A monk with guns is doing some 
Matrix or 
Equilibrium stuff, and if you don't think that's a cool image, I don't know what to tell you.
A rogue with a gun is fine. 
Pirates of the Caribbean, eh? Or maybe a more modernish sniper flavor would be appropriate, I could see the protagonist in 
Enemy at the Gates being a rogue.