Worse, people shopping for presents are going to be less discriminating than people buying for themselves. Christmas gives rise to this entire temporary economy based around manufacturing and selling crap that no sane person would buy and keep. The shelves are lines with light-up ties, Chia Pets, and Deer Hunting games. There is no limit on how much kitschy crap you can sell if you've got a determined marketing department and an icy vacuous hole where your soul should be.
If you're a publisher and you're worried your game might be reviewed unfavorably, then release it at Christmas! Reviewers won't look too deeply, if they manage to review the game at all. And even if it does get savaged by Metacritic or sodomized by Yahtzee, shoppers won't be paying attention anyway. Christmas can guarantee that your buggy cookie-cutter game can get a decent slice of the December sales pie-chart no matter how much it sucks.
So, release your strong games in summer and your crappy knock-offs in December, right? Not so fast. The season does have winners and losers, and some games do end up doing far better than others. This week Ubisoft's Michael de Plater told GI.biz, "It's a bit tough to launch a new IP exactly at Christmas when you're head-to-head with blockbuster sequels. [...] It's interesting to see a number of big titles, like Heavy Rain, being targeted at 2010 to avoid the Christmas rush." So, Christmas sales aren't really about quality, they're about brand recognition. People will buy an entry in a famous franchise over a hot new property, more or less regardless of their relative quality.
Obviously, this Christmas mess is bad for the industry as a whole. Low quality titles sell well. Innovative stuff gets overlooked. Game reviews are less comprehensive. Sometimes publishers will rush a game out the door for Christmas, thus taking what would have been a fantastic game with mediocre sales in March and turning it into a mediocre game with fantastic sales in December. For those of us who play games year-round, this is the exact opposite of what we want. We keep clamoring for less sequels, less knock-offs, more polish, and more innovation, but who are publishers going to listen to? Us, or a pile of money?
Nobody has any motivation to change anything. Sure, you could release your game in August, but your game will really have to stand on its own merits. And even if it performs well, you're letting your rivals have a bigger piece of the December pie. You'll be taking on more risk while helping them make more money. What we have here is a Nash Equilibrium. The industry as a whole would be better off if sales were spread more evenly year-round, but it's not in anyone's interest to change their behavior.
For now the industry is probably going to continue its practice of holding games when everyone is on vacation and then releasing them all at once when nobody has time to play them. Merry Christmas!
Shamus Young is the guy behind this movie, this website, this book, these two webcomics, and this program. His actually really looking forward to his first Christmas in twelve years where nobody talks about Duke Nukem Forever.