I believe the Mayans just needed a stopping point. On a calendar, a pretty good stopping point would be a solstice. Did people expect them to make a calendar that went all the way to the year 6792? No, they got their point across with a calendar that stopped in 2012. Conspiracy theorists have just hyped this thing up like mad.
At the end of the day (world).. it's all about FAITH. Not believing in something doesn't give you the right to mock those who do. What Would Mayans Do? TSK