I went to D2 because I didn't want to be the slowest guy on the team at a big D1 and the in-state mid-majors were worse academically than my D2 school where I got a full ride. I also was able to get into a good grad school and by going the D2 route, I was able to get 7 years of good (not great) education without paying a dime.
In my first XC season, we were a borderline top-10 D2 team and had a winning record against D1 schools including beating Mizzou, Kentucky, Mississippi State, Auburn, Vanderbilt, Miami, Georgia Tech, Tulsa, Chattanooga, and Arkansas State, as well as a ton of directional mid majors.
That was the good part. The bad part is most of that "success" was on the backs of 3-4 good foreign runners and when they moved on, the foreign runners we brought in to replace them were not nearly as fast and we sucked for a few years. The other bad part is I watched two D1 teams who had offered me a walk-on spot win a National Championship while our team didn't even make it to D2 Nats for a couple years.