In all due fairness to Left 4 Dead it did have stiff competition on the console during the time frame it launched. The game had to face the likes of Gears of War 2, Fable 2, and Fallout 3. While the likes of Uncharted didn't really have that level of competition on its respective platform.
Yes the reaction is overblown. However I have no real problem with that either. Kicking around the members of the Sony Defense Forces has been less then rewarding over the past year. They kind of rolled over and played dead. This development has reinvigorated the stupidity. They are going to rush head long right back into the meat grinder for another go. Seemingly having forgotten what happened last time.
They aren't even appreciating the fact that the PS3 is now old hat for gaming enthusiasts. It is not the hot shit it once was where die hard platform fans had to have it, and were forced to wait to buy it until it reached a cheaper price. There isn't anyone on the fence anymore as far as I can tell. Nobody just sits on a fence for three years waiting for a console to reach a magical price. They either ponied up to the higher price, went elsewhere, or went to do something else.
The lower price will help, but your not going to see a super massive spike like you saw in the past. You are going to see a twenty or thirty percent increase in sales, and that isn't necessarily going to leap frog the 360 for Sony. I think it will just be a few thousand units difference per week until the holiday season. Where the 360 really just picks up massive steam. Remember that December is really about North America.