They don't disallow LOI. It's just that in my situation, it isn't a significant LOI because of my no acceptances. It would not mean a whole lot because I would surely matriculate there if accepted. Also downstate asks that students refrain from contacting admins about app status and to just wait. What I did, however, was pay for and send all 5 of my transcripts and complete all the prereqs of admission on their checklist so that I'm ready to go if they extend an acceptance. Surely that shows I am interested.
About geography, family is important to me and I really wish to stay in-state. Could I have applied to other states? Yes, and I probably should have because it would have increased my chances and maybe resulted in an MD. But I do not like to look in the past and at this point in time, I have a DO acceptance. So between waiting a year, reapplying w/o changes in my application/possibly moving far away and accepting a seat at a NYC DO school a train ride away, 5-10 minutes away from both of my sisters' current colleges, and near my support system? I will take the latter. I hope my experience helps someone reading this that may be in a similar situation now/will be in the future!