You know what's nice about 16gb for gaming? You can run 2 or 3 different games and they'll always be in memory so long as you don't reboot your computer. The games that you play the most will load up instantaneously. Not only that, but you won't get any disk thrashing when you alt-tab out of one or even when you quit the game. To me that's a big deal.
That sounds pretty cool but I just got a nice new 256 GB SSD, so I wonder if it would still help some....