Well I think the rationale is, if you weren't accepted the first time, is there anything significantly different? If not, it really isn't worth their time to pursue it further. I'm not saying that this is your case, but just in general.
In regards to UCSF to UMN, it's just a secondary, even if it's just the UCSF one. Also not ever school is looking for the same criteria or weighing them the same. For example UCSF is a fantastic research institution and they may have really liked that in your application (especially with 5 publications!). While the UMN is also a strong research center, they're also one of the top primary care institutions, and you have very limited patient care experiences and this is probably one of the reasons they rejected you last year.
Concerning your medical experience, it is like tonicX2000 said, they only have so much information to work with.
Plus, with just about any clinical experience you'll have the chance to talk to patients, residents and other physicians. If you are with any physician that gives a damn about you, you're going to be treated like a medical student and they will do their best to teach you as much as they can. Your experiences aren't that unique or special, and if you think that 150 hours of shadowing, no matter how involved, is all you need to have a solid grasp on patient care you're sorely mistaken. Medical students on preceptorships don't do much more than dip their toes in the pool, that's why it takes years and thousands of hours of practice. I'm sure you had a great experience, especially since you have just about no other clinical experience, but to say that you're sure that your experiences shadowing are for sure more valuable than jobs in the medical field such as scribing, CNA, EMT, etc is just arrogant and ignorant. You have no idea how much better many of the students who come in as scribes or with other medically related jobs work with patients. It's honestly like night and day. If/when you actually start working with patients, you'll be surprised by how much you can learn by just laying hands on a patient, talking to them on your own terms, and actually providing some care.
Communication skills and prerequisites are just that, prerequisites. Just because you got interviews doesn't prove anything. There are plenty of applicants who get interviews who clearly aren't cut out for being a physician. The way you've said things seems to demean the rest of us who applied to the UMN. I'm happy that you got a secondary at UCSF but don't make the UMN out to be some second-rate institution. I'm sure you'll get in somewhere eventually, and hopefully your mindset will change, but all you've communicated here is your anger and sense of entitlement.