GPA over the most recent 60 hours is one of the most heavily weighed stats on the application as it tends to indicate what kind of trend you are on when compared to your overall GPA... in most cases it also includes the majority of your upper division science courses if youre a bio major which many applicants are. I'm a previous medsci/current med student and this info is from when I met with the MedSci program director a little over 1 year ago.
This program recognizes that a student 3.7 gpa over the last 60 hours, a 3.3 overall GPA, and a 30 on their MCAT (old scale obviously) is a capable student that had a rough start to undergrad but will likely get screened out by med schools due primarily to the lower cGPA. For these students, MedSci is the perfect way to both increase their overall GPA, but also prove to AdComs that their lower cGPA is not truly reflective of their capability. I cant tell you how many of my classmates had a scenario similar to this.
If you put yourself in the shoes of the program, it makes sense to accept students like this. Their goal is to accept students that they believe will appeal to med schools and eventually succeed once they are there... but need just one final push on their app to get them there. Additionally, they realize that students excelling in their most recent 60 hours, again... probably your upper division science courses, will have a higher chance of succeeding in MedSci itself than someone struggling to make A's in their undergrad bio courses.