I understand, but think about sports for a second. You can't just take up a sport (even though it will prove to be good for your health) and go all the way, there has to be a begin point where you take things slowly and then you build it all up gradualy. That's pretty much what I meant with the 'dangerous' part. Pranayama is mainly practiced in certain asanas and when your body (and lungs) are not used to this kind of practice it can prove to be dangerous in that way that it can cause you great physical pain...
And I believe that this is especially the case in this 'new age' area: I think that you are overestimating people when you claim that even new agers know this.
We are in an age where information has been spread all over the globe...so ancient wisdom is suddenly revealed to people who have been living entirely different since a very long time in history. That can be dangerous. (Just think about certain drugs *or what they can arise* and how they are being used in this chaotic modern world.) Anyways, my point being is that people do have access to the more advanced ways of pranayama and there will be people trying this out, afterall, how many sadhu's haven't 'testified' about the siddhi's one can attain by pranayama or yoga and somehow I do think that there will be people out there trying to hold their breath etc etc without really knowing what they are doing.
And about the kundalini: I think that there are more ways of awakening the kundalini force than by pranayama...I even believe that it can be awakaned without even doing any kind of exercise. Why ? How ? Of that I have no idea but I'm convinced that it has happened before.
This all said: I also wouldn't want to discourage anyone in doing breathing exercises or yoga because it 'could' be dangerous. Life in the crazy world is way more dangerous on a daily basis: polution goes beyong our worst nightmares, the planet's being raped 24/7, people are exploited 24/7, they are being programmed by other people that only have their own best interest in mind, our food is being grown in poluted ground or worst slaughtered with the excuse that it is so nutritional and that besides that it is our instinct, kids are taken away their innocence because it's profitable etc etc, now THAT is dangerous and health and mental threatening...so I strongly encourage every (positive) action that will uplift the human spirit and make it transcend the mess that we're in.