Im of the opinion that guns can be interesting in rpgs if done right. I happen to favor party based games with guns moreso than solo character ones. I dont really know why, but it can sometimes be fun. I still love my fantasy based rpgs more because Im medieval regarding that. The cool thing about guns in party based games is that you can really mix things up and make tactics fun (especially with turnbased games).
Whereas in usual party games, you still have roles in the game. Tank is still a tank, except instead of a heavy sword and strong armor, he's got high health and a shotgun. DPS is usually a rifleusing marksman or even a pistol user if you dual wield. Then there are smgs and uzis. Basically, it can be alot of fun playing games like that and yes rpgs can broaden to using guns.
Fallout is probably a good/best example where guns are present. I happen to think that if tactics was done with a sequel/more games it would be excellent. I really liked what they were doing with party combat in that game. Screw real time, I still played in turnbased.
Guns are only for cowards when attacking people who don't have guns, or creatures that will just tear you apart (Radscorpion, anyone?).