It can be a risky business judging another civilization or an older civilization by our own standards. They were probably founded and built on entirely different principles and values. Yes, the Mayans got a lot of things wrong, but our own [often uncivil] civilization has gotten so many things wrong:
A) As far as any evidence is available, the average educated person alive today has a greater scientific understanding of the processes of our solar system and galaxy than the most informed Mayan during the Classic time.
B) The only reason these theories are given any weight (however light) is precisely because we're judging them by contemporary standards and allowing modernity in to weight their achievements. If the Mayan hadn't developed an advanced civilization with some incredible achievements - "advanced" and "incredible" as judged by their successors, these theories would be even more dismissed. Are you comfortable giving them some credit by todays eyes, but not taking others away?
C) While I agree it is very risky to interpret through contemporary perspective much of what makes up a distant pasts social/cultural/artistic/religious/philosophic worlds (though we're having this conversation based on several individuals feeling comfortable doing just that), if we use currently accepted terms to discuss these theories, this threads subject either falls in the religious or scientific spheres. And it should be judged accordingly. If the former, you can believe the Mayan have some gateway into future galactic truth and most of mankind is doomed... and have fun with that. It doesn't matter anything else said here or elsewhere. If the latter, and we're answering specifically the questions of if they have insight, and if we should become prepared for an [at very least] massive global change in 2012, then we should use every available contemporary scientific advantage (even if flawed by future perspective - assuming the future is mostly ahead of now as now has mostly progressed beyond the past in scientific knowledge) to judge the theories* as harshly as possible, no?
There are certainly a variety of ways to getting to know parts of the Mayan knowledge base and belief system, but the questions posed here about mankind and Earth are primarily scientific aren't they?
* Theories, plural, separating the evidence for possible events in 2012 from the possibility the Mayan, Hopi, etc. have insight into them.