Bravo againMy best answer fo this is that the idea of a Great Mother Goddess had two separate but related period of evolution. One was in the late 19th century, where it represented the primitive, ecstatic but ultimately irrational practices of the world before Western white males took it over : nice, but needing to be left behind, just as you can't stay with Mommy all your life.
The other time was in the 1970's, when it arose to serve as a counterweight to patriarchal ideas about a male, paternal, dictatorial, God, and the related world view that women were inferior, morally and spiritually. A benevolent mother goddess who thought sex and women were both nice and not in opposition to spiritual realities, was a wonderful empowering image. (The real problem with this was that the Victorial manifestation of the Great Mother provided the seemingly feminist, but often reductionist, idealogy behind the modern version.)
Even if you didn't believe in the Great Mother, it was a really nice idea. So it was projected into the past. Now the average modern woman didn't have to believe in it because all those other ancient people did.
In the 1970's, belly dance also took off in the West, or at least in the US, one of the reasons being that it too supported an integration of sexual, sensual, emotional and spiritual. Western women used it to integrate those things in their own lives. Regardless of its meanings in the East, that was how it evolved in the West.
So it's not too odd that belly dance and the "Mother Goddess" became involved in popular culture. For those who weren't there, and didn't have to hear about the "sultan's harem" and so on, it may be hard to imagine how great it was to have this alternative view that was also understandable by the general public. No one thought it was wrong, but no one really wanted to puncture it either.
I agree that the time for this is past. In fact one of my earliest Habibi articles, back in the 1990's, was on how we should seek the origins of this dance in the social history of the 20th ccentury (New Page 1 under articles). OTOH it isn't stupidity of individuals that caused this view to develop, it's social forces that we may now be almost ready to leave behind.
If anyone wants to read in-depth about the evolution of one motif, the dance of the seven veils, from the 19th century into the modern era of the belly dance community, I have an article on it in Anthony Shay and Barbara Sellers-Young, Belly Dance: Orientalism, Transnationalism, and Harem Fantasy (Mazda 2005). Just for a little light reading ...
I am reminded of an archeologist ( can't remember his name right now) who was talking about certain metaphysical groups who always want to give credit for the building of the pyramids to either space aliens or the use of heavy duty magic. What he said was that in not giving due credit to normal human beings for both conceiving of the idea of pyramids and actually building them, that they are greatly denigrating the human soul, heart and mind. These structures were built by humans, for the very human need and purpose of achieving something lasting, either in the form of the structure itself, or in the preservation of the human body and soul.