What's wrong with electronic shutters?

Just read this : http://myphotomoviecam.blogspot.com/2009/02/whats-wrong-with-electronic-...

I wonder if someone already thought about puting an lcd shutter system. It would be a single pixel big lcd plate in front of the sensor. This would be electronical and still let the sensor do it's job without mechanical parts.

Nvidia does this with 3d glasses : http://arstechnica.com/gaming/news/2009/01/ces-2009-nvidia-shows-off-3d-...