Different people probably have a variety of reasons. Cost isn't always everything and in some cases you get what you pay for. Someone could have gotten into an MD school or they might live very far from Erie which could mean leaving family + friends behind
In my case: LECOM is very young so they are still working out issues within the school and with rotations. I asked my friend how he likes it and his response was discouraging at best. Their board scores might be really good but I have heard the student voice is not heard as well as it should be. I did not like that the anatomy labs were prosected. Although minor I did not like the dress code or food/drink policy. I understand why those rules are in place but I like my coffee and breakfast sandwich in my AM classes. I also want to do research and there are few opportunities at LECOM. Even though they are there the paid positions will probably be filled, you might not find productive research (multiple publications) and you might not get to do research in a field that interests you. I also prefer the location of the school I chose, I understand free time is very limited but when I have it I want to make the most of it with my interests.
LECOM is a very good school and I have no doubt those that choose it will succeed and as you said is probably the best bang for your buck. However, it just did not fit my preferences as much as PCOM did.