The lower dantian, or hara seems to be the key factor in characterizing most taoist and zen meditation. It seems to be the great secret, focusing the yang on the yin, to create unity. Zen master Hakuin learned this from a taoist hermit. Zen goes on to use this as one of the only "explained" techniques, and prizes it as the source of zen.
For some time I have been suspicious that there is some kind of conspiracy to keep people "up in their heads" by focusing on the third eye. Especially in the west, there is a vast number of traditions, teachers, subliminal propaganda, media, music, and movies that are aimed at the third eye. It seems like this creates lots of confusion, not to mention headaches, as focusing yang on yang would create an imbalance. The turtle school vs. the crane school for example.
Ofcourse, non duality is key, but I am interested to hear peoples opinions on this.