Like we've been hearing for so many years, this whole process is a crapshoot. Some of the most qualified people I know didn't get in anywhere on their first try or didn't get in until very late in the application cycle. Also, you just can't predict which schools are going to decide to interview you. The initial interview selection process is something we can't control. At some schools it's mainly numbers based, whereas at others, more emphasis is placed on letters of rec, activities, personal statements, etc. I've also heard that some lower tier schools don't give too many interviews to applicants from the top schools with extradordinary numbers. The reasoning behind this is that the school knows you're more than qualified to get in somewhere, and even if accepted, you probably won't matriculate at their school. No one likes being used as a backup, so they hesitate using an interview spot on someone who's not really interested.
I totally agree with the whole personality component of the selection process. Med schools don't care about your killer stats, multiple research publications, or the 500 volunteer hours you've logged at the local hospital, if your personality rivals that of a two by four. If that's the case, you're probably not gonna be getting in, and rightfully so. Medicine, as much as it is a science, is also an art; one which entails being capable of relating to other people, people whose ideologies and backgrounds you often know little or nothing about. That's why schools want students who not only possess the academic ability to excel in medical school, but more importantly, the prerequisite social skills to thrive in a clinical setting.
Making a connection with an interviewer will only help you, simply because the conversation seems to flow much smoother without those awkward pauses. It also leaves the impression that you're more than just a set of numbers when your file is brought before the adcom, and your candidacy for admission is thoroughly debated. Also, there are a ton of things that you can do during an interview that can get you rejected. One of them is being arrogant. In an interview at a top 20 school, one of my friends was asked what he thought his weakest science subject was. His response, "I don't have one." Now, this was an honest answer in his opinion (cause he's aced every single class out there), but his delivery probably came off as cocky and arrogant. It's a shame to lose an acceptance because of things like these that you can control.