The only real difference I can think of is that most new games are designed for widescreen (1920x1080) so if you have that, all the interface elements will be in the right spot, etc...
Bioshock and the Witcher 2 come to mind as games where there was a big todo about it.
With Bioshock, people with widescreen monitors were upset because there horizontal view (what they could see side to side) was the same as a regular LCD, only with the top and bottom of the view reduced.
The Witcher 2 shipped with only 16:9 support and added black bars to 16:10 and 4:3 screens.