But the wiimote is not accurate at all. You have to watch the pointer on screen to see where your pointing. It's very difficult to get a perfect distance from the screen to make the pointing of the wiimote match up with the location on the screen and there's much more lag.
The old light guns did not require a pointer on the screen because they were perfectly accurate.
I love my wii, but it's not a good replacement for true lightguns.
There is certainly a weakness in the way that games implement the Wii remote pointer. Since there isn't a direct connection to the screen, the options are either to have a calibration step, or to either use a cursor/reticule and let the player's brain compensate for the discrepancy. Everyone opts for the latter because having to calibrate pisses users off and is probably why the Super Scope failed. FPSes opt for a variant which treats the remote like a mouse on a PC FPS, and this is arguably the most immersive option.
The cursor technique is where you see lag. There really isn't much lag in terms of processing angle of the remote. But in order for the cursor to be usable, it needs to have continuity of motion. Smoothing its position as it moves around on screen introduces a delay, and that's why it feels laggy.
But in principle, there's no reason that a game couldn't have a calibrated mode that would act just like an old light gun. Players would just hate it.
The old light guns did not require a pointer on the screen because they were perfectly accurate.
I love my wii, but it's not a good replacement for true lightguns.