The ushers usually take up the collection and, traditionally, ushers are men.  I think many people would just think it unseemly to have women taking up the collection since it is done during Mass.

Other than that, I don't know of a reason women couldn't be used to take up a collection though I don't think men who are willing to do so should be sidelined because a woman wants to do that task.  I'm sure there are many tasks a chapel needs done that women who want to help could do.

It's just unseemly for a couple of women to be ushers -- which includes directing and telling each man where to sit. Men are supposed to be the leaders and directors, at least in a traditional, non-feminist society of any kind.

It might be because ushering is done in the church during Mass. Women need to take a more "supportive" role in anything during an active Mass. So that still leaves plenty of ways they can help: prepare vestments hours beforehand, clean the chapel, do sacristy work, flowers, altar linens, prepare/serve/clean up refreshments in the hall, etc.

Just FYI (to include the OP, too), we women in our parish do not prepare vestments.  The oblates do. If there are no oblates in a parish, the older male servers can prepare them. 
I'm not sure what "sacristy work" entails, but the only real need for us women in the sacristy is to pick up soiled linens and then return them neatly after laundering.  Overall, the sacristy i.m.o. should remain a men's area, as only men vest, only men are directly involved in liturgical celebration.  When I do return linens, I'm really turned off by the occasional clueless woman who enters the sacristy for the express, sole purpose of chatting it up with the oblates and servers, especially since they attend the reception, which is where she should talk to them, NOT in the sacristy.  It's very out-of-place and very selfish.
It is true that the task of cleaning would reach to the sanctuary and sacristy as well as the pews, and also that those who prepare flowers (females) need to enter the sanctuary, but in general the female presence within the church proper should be as minimal as possible.
So I'm mostly just agreeing with you, but especially the part about the OP's question:  ushering.  Unseemly indeed, because it's a leadership role suited to men.

All the other work we do is also behind the scenes, largely domestic work:  sewing, cooking, pressing.  However, a few of us have artistic talents also, and those are used in a service capacity, when requested.

I always figured woman should be doing the up keep of the church (cleaning, vestments care/sewing, flowers), and church fundraiser running. I just never think women should be up there, or have any sort of role like that during mass. They should be sitting with their families.