In theory, this would eliminate a lot of problems and seem to be the perfect solution. In reality, from the Navy's POV, it's just not practical.
First, the Navy doesn't actually believe that they have enough women that want to volunteer for sub duty to man a sub, even a fast attack. Not in the right rates anyway. Billeting isn't just about getting somebody on the boat. It's about getting the person who can do the job in to do the job who has the proper training. So, even if they could find 150 women who want to go subs, they probably wouldn't be the exact women needed to properly man and operate the submarine. Getting enough women, with the proper qualifications, could take a long time.
Second, some of the jobs on subs are only done on subs, so there would be no chance for the women to get OJT. And some of the equipment found on subs is a lot different than that found on surface ships. Learning to operate the equipment takes time. They wouldn't have anyone to train them. Sailors are not qualified to do much, even if they have gone to school, as soon as they get to their ship. Learning to operate the equipment and essentially run whatever part of the ship you're responsible for takes time, and your teachers are those sailors who have been doing it. Who would teach the women how to run the sub? Being fully qualified to operate some parts of the sub can take as much as 18 months, and that's when you have most of the rest of the personnel already trained, with experience on things that might go wrong.
Also, it would take a long time to get the women-only sub operating at the same level as the male subs. I doubt the Navy would be willing waste that much time and money just to have a female-only submarine. Not to mention they probably wouldn't be willing to risk the sub.