well a real light gun tracks the position of the gun in relation to the screen.
the Wii remote track the position of the gun in relation to the sensor bar.
so if your TV is 5inches wide or 50 inches wide doesn't matter to the Wii because 1degree of adjustment moves the pointer the same % across the screen.
No matter what size or shape screen you're using with the Wii it never "shoots" where you're pointing it because for all it knows you don't even have a screen to look at.
unfortunately traditional light guns don't work on anything but old Tube TVs, they do make legit "light guns" that work on a more advanced system than what Nintendo uses with large sensor bars on either side of, or completely around the parameter of the screen (this is how projection arcade machines do gun tracking)... the only proper light gun setup like that I've seen was a 3rd party accessory for the PS2/PC.
I have no idea idea what the Time Crisis 4 PS3 gun setup is like but I would HOPE it's IR based... I would suspect the reason HOTD being released for the Wii is two fold
1. everyone who owns a Wii alreay has a "gun controller" meaning the game can be released without one at a cheaper price (=more potential sales)
2. the Wii has a larger market share (=more potential sales)
I'd totally buy HOTD4 if they released it with a gun controller for the 360... but it doesn't look like that will happen.
