People are irrational in so many regards, and put far too much value in the symbol of getting something at a certain point vs. getting them when its most advantageous to all. A family celebrating christmas a week later would have the same experience but with cheaper gifts, or better ones for the same price.
Presents should be given post-season in order to be able to buy them on sale. In this economy anything would help to give people extra money in their pockets. I think if you are not up to the ideal of giving presents after the holiday then some items can be bought and given next season.
Presents should be given before the season so that the people are able to get it while it is on sale and save a lot of money. Plus than people get to enjoy their present before the holidays which means they can enjoy their time off more and longer because they have something new.
I think it is fine if people chose to celebrate holidays post season in order to get gifts on sale, but I do not think it should be that way for everyone. If everyone waited to buy presents until post season, then the sales would just wait until after most people buy gifts any ways.
Buying presents for people post-season for a given shopping season is not genuine. It makes a person seem cheap and unreliable. The fact of the matter is that a person should buy gifts during the proper season rather than waiting afterwards just to take advantage of some savings that aren't worthwhile.