The entire point of this is not for apple to get another almost-dollar from you, but it is to get you familiar/comfortable with the mac app store. Once they have you there they can sell you all sorts of other items.
In the business world, this is tantamount to a "loss-leader"
I really don't believe this is the case. The Mac App Store has been up for a few months now and is doing pretty well. People seem very familiar with it.
This is a classic Apple move charging you for a premium, in this case HD video chat.