This is a no-brainer change. I always have wondered why this is not the case. Do the people at NCAA that determine the schedule not know how hard it is to run a couple of 10k's so close together? I know for a fact that NCAA has plenty of good distance runners working for them, not sure how much influence they have over determining a post-season schedule.
Another no-brainer change is extending the women's race to 8k. The 6k distance just turns the race into a sprint finish every year, not really a long-distance cross country race. Why they keep it at 6k is beyond me.
The slippery slope argument is rarely a strong argument. I could imagine athletes that good enough to compete for top 3 at USAs would just get kicked off the team or pursue a pro contract if they decided not to race at NCAAs.