I was just thinking of what I would do if I was coaching a high school team (something I'd love to do some day when I can fit it into the rest of my schedule) and I'd definitely prefer to use time on easy days for high schoolers. To be able to say experienced runners, 45 minutes easy; less experienced, 30 minutes easy. I could still see guys trying to race each other but the temptation to run the same loop faster and faster each day could be taken away to some extent at least.
Of course, another important thing I'd do is stress on every easy day something else you mentioned. Do you want to be fast on your easy runs or in your races? You can't have it both ways.