First and foremost, money for big business.
Then, an excuse to be a little nicer, 'cause normally people are fucking pricks.
Then, a reason to get drunk.
It also means family, and having to see them. Which for most is traumatic.
And often it means eating until you hate food.
This is what it means.
What should it mean?
I'm not sure I'm arrogant enough to hypothesize that it should mean anything other than what it already does. The idea of taking it too seriously contains the same pitfalls taking anything too seriously does. (Except for the Atari game Pitfall, which you do have to take very seriously, because the pitfalls are actual pitfalls.)
I'd like to think that people take advantage of the positives, but if I could chose one thing that it should mean, it would be that the holidays shouldn't be all that special for the good reasons. It should be an example of how you can feel, how thankful you can be, how well you can handle your parents, how nice you are to others. And it shouldn't be any different for the rest of the year. If people behaved like it was the holidays every day, maybe we wouldn't have horrible things like celebrity dance shows.
Short Answer: The holidays should mean less, but should set an example for better behaviour.