It would have been really cool... I mean the zapper brings back so many great memories of capping ducks, and trying to kill that stupid dog. You got the Zapper, the Menacer, justifier, Sega Master light phaser, the Super Scope, the Saturn gun, xbox gun (sucked) Guncon, Guncon 2, Wii gun, ps3 (not sure about xbox360) and there maybe more!
We love our guns especially in America, so it only seems natural to have the light gun and bring it to kids. The turbo grafx is, in my opinion, the most notable video game system without any kind of gun. I don't think it would have been a bad idea, or as risky as you may think... Parents may be the only opposition to light guns, I doubt any kids would have been against it...
I think it could have made the TG more popular here in the states...Imagine how sleek it could have been, with a laser pointer, and it could have clicked (like the point blank arcade guns) and the colors and sprites, mmmm... Gunboat could have been cooler...
I say, lets make it happen....
-Alex