Back in the day, playing in the mud was fun, and to add on to what Dumfries said, and looking at the picture Thor posted, restoring a field back to good condition is very expensive. That includes the number of man hours involved in the work. And it may take years to fully restore it. Until it is restored, the field is useless. Schools that cannot afford to fully restore a field, will do patchwork repair. That, in my opinion, puts student athletes at far greater risk than the turf. Too many have these visions of their schools having had perfect fields like many NFL and college teams have, and that just is not the case. In the bigger picture, the new turf fields are safer, and save districts money.