I also have a problem with women in the military.
Many very good reasons have been given already so hopefully I will not overlap any of them.

One major thing I see about women in the military, is the fact that to accommodate women, standards by necessity need to go down.
One example of this is if the average in shape women is between 130-145 pounds, how can they aspect to carry a back pack that a male of average weight carries?

A back pack in some cases can be the difference between life and death, if they don't have enough supplies they will not survive.

Tom