its both justified and unfair though: if too much opportunities existed for rural people urban players would complain, or the rural areas will suddenly get a lot of passerby/visitors from nearby cities all of a sudden, which probably would be unwanted. not really much you can do there.
i feel like they do a good job of equipping every major town/city though with pokestops and gyms and random spawns, so its a matter of getting an opportunity to go there to explore