I don't know about unis, but in training centres I'm generally ordered to dress down. Foreigner very informal, very cool, formal clotheses not you foreigner culture.

I think ties are kinda formal and uncomfortable to wear all day. My office liked us to wear ties. I hardly ever did. I'd wear a nice shirt which got tossed as soon as I got home. Most offices don't dress so formal. In many offices I think the women look like they are going to the cottage, not work. I find in general we dress down. It's hard to find nice dress clothess, at a decent price or often at all.
 Lets flip this issue over, I can not remember the last time I saw a nice looking woman in a dress at home. But in China,, OMG.

Nope

No.

When someone can prove to me that wearing an uncomfortable phallic symbol around my neck makes me better at my job I will wear one. I am not a tie man at all, never have been and am happy to say I have played a small part in slowly changing the attitudes to men wearing them where I work in Australia.

So a big NO from me.......

For me, it depends on the kind of university or school you are teaching at, and whether or not the Chinese male teachers are required to do so. 
If you are teaching in a Police or Military university here, then answer is most definitely yes.
If you are teaching in a language training school, then probably no.
Now, if you do not wear a tie, I do feel that a "nice" shirt is a must. No tank-tops,  or t-shirts.  
My two cents, er, two mao's worth.

I don't actually see the point of ties anywhere, ever. They look like a noose to me, and I'm very thankful that women never have to wear them.