I would guess it has to do with the fact that women dont really have any level of importance here, especially in politics. The social status and concept of equality for women is still n ot quite up to what it should be.

On a similar vein, I have always wondered why is it that when world leaders get together in a "black tie event" (tuxedo) the Chinese are always underdressed, (they just wear a  suit). It certainly is not ignorance.

The first chairman had some problems with one of his wives gaining power. This has led to a tradition of not allowing the women out in public. 

The current top dogs wife do make public appearances. Didn't she give a concert recently ? This is of course void of any politics. 

Jiang's wife was too .......to get publicity while Hu's wife kept a low profile.That's the real reason.

My wife told me she read that the 1st lady  will sing in Russia at a gathering and perform in Chinese and Russian

maybe between her and Mrs Obama they can keep their husbands inline and do some good

I keep getting this image of the Flintstones   instead of Betty Barney,  Wilma ,and Fred

Well you get the picture