At what time of the year were you there? Especially when wet after summer thunderstorms, the roads get torn up rather quickly by the relatively heavy traffic. The roads are wet during the winter during warm spells, but traffic is lighter and often everything is frozen solid.

Somehow I doubt that New Mexico worries very much about preserving ruins managed by another outfit. Having worked there, I can assure you I would prefer to see at least a light duty paved road (getting groceries is much easier). When traffic gets heavy enough, pavement is less environmentally impacting than a graded dirt or gravel road.