Lots of good and varied perspectives and food for thought in this thread. However in this debate and decision process, in which I have years of experience with student-athletes, two points consistently stand out:
1) Don't assume anything.
If you're a top hs runner, don't assume you have to or should run D1. If you're a decent hs runner, don't assume you can't run D1. If you're an excellent student, don't assume running D1 will hurt you academically or professionally. Take time to think it through. Talk to people -- lots of people with different perspectives. Look at, and really investigate and consider, a wide range of schools, running programs, and coaches. More often than not, the people who regret their choices are those who failed to honestly consider a wide range of options in the first place.
2) Regardless of how good a hs runner you may be, don't fail to seriously consider the D3 route. D3 is a huge field with a huge range. Unless you're legitimately looking to make a national team before you finish college, you can find plenty of competition in D3 if you look at the right programs and conferences. Of course there are exceptions, but in general the coaches are better, they care more about the individual student-athlete, the injury rate is lower and the recovery rate is higher, and the frustration factor is much lower. And just as there is a huge range of programs, there is also a huge range of schools. Choosing D3 doesn't have to mean you'll be going to a small liberal arts college and coming out with a worthless degree that won't get you any job interviews.
Bottom line -- As a 16 or 17 year old high school junior, this is the most important decision you will have made in your life, up to this point. Don't make it in a haphazard or lazy way. Think. Do your homework. It will be well worth it.