My observation was most MD schools are in large metro areas while many DO schools (not all) are in more rural areas which makes sense based on your explanation as MD schools have residencies and research which needs larger academic hospitals while DO schools seem to be focused on the pre-clinical/clinical education (mostly seem to be pre-clinical as they usually may not have affiliated teaching hospitals with all required specialties located near schools).
For the reasons that you cited, since KC metro has >10x population of Columbia, I would have expected more departments/larger student population at UMKC than Mizzou. Even now, I think Mizzou students have to go to springfield for clinical rotations for probably same reasons - like access to diverse patient experience/larger hospital to accommodate all students. So I find it a bit surprising that UMKC doesn’t have as many clinical departments/funding as Mizzou - may be because KU med school is nearby (from meeting the needs of local population perspective). If you contrast that with Indiana the combined size of the med school and number of campuses (didn’t realize there were 9) may help to secure a lot of funding from NIH etc. (which may be reflected in their ranking)
On the flip side, a teaching hospital in a rural area may bring medical expertise/more money/jobs to the rural community (as teaching hospital may get usually gets higher reimbursement). This is where IN model is attractive as it spreads the increased revenue across all geographic areas in the state and not limited to larger cities.
Usually IN, IL BS/MD programs were limited to in-state students. If this new program is open to all, that will be interesting as IU is higher ranked school though MCAT requirement of 512 for the program seems to be same as their average MCAT.