All the feedback from the summer cruises that the mids go on, seem nothing short of a ride in an amusement park. They all come back very motivated and excited, but many of them have not had to lead people.
I think in this case you are misinterpreting the purpose of summer cruise. From my perspective its not to get you to a position where you can run a division, its to put you in a position to understand how a division/squadron/etc is run.
CORTRAMID certainly is a good time (so I hear, I opted out of it) and is generally considered to be where you make your choice on the community that most interests you. Your other cruises build on that experience, but they are just to give Mids a little bit of experience such that they are not going into completely foreign environment come commissioning.
I dont know your personal situation, but we have several Mids at my unit who have more sea time than our E-6 OC's, which may not be a substitute for 7 years in the Navy, but it does give them a different and completely valid perspective.