We used the draft in WWI and WWII and won both wars. You can provide no reasonable evidence that the casualties would have been any lighter had women been used, or an all volunteer force was used. Most platoon, company and battalion tactics call for merely the presence of someone who has the upper body strength to perservere, and do thing like throw a grenade farther than its blast radius.
There is no evidence from past experiments that indicate women in dangerous roles in combat, other than when they have to fight at the last ditch end (and then no evidence that their contrabution preveiled) produce positive results.
Our military has not proven itself vastly superior to all others with this set-up. This setup is entirely experimental, and contrary to what we know has worked in the past. Why do it for such chancey consequences and such a feeble possible return?
A strong military and personal choice and responsibility are conservative ideals, so my position definetly isn't liberal.
But what you are advocating is a weaker military, based on historical successes. Personal is choice is not a conservative concept. Just ask anyone who want to put certain substances in his body without permission.
Actually, I think the opposite is true. The Marines are the only branch of the service that trains its male and female recruits seperately and they are the only branch of the service that consistently has no problem meeting their recruiting goals. Young males seek to prove themselves as men and surviving a challenge like boot camp is one way to accomplish that. When females can meet the same (not really, but let's play along with the gender benders) challenge young men are less interested because they cannot prove their masculinity (if a girl can do it...).
BTW, I am an activated guardsman in Qatar (previously in Iraq and Kuwait). We have females in our unit and by and large they do fine, but there is no absolute need for females in the service at all.