Hmm...an urban setting being the start of a Pokemon game instead of a small rural town would be a nice change and would have an interesting impact on the storyline. Not everyone who wants to be a Pokemon Trainer comes from a small, sparsely populated town. XD Though I'm not sure how navigable Hiun City is... but yeah, I'm sure there are lots of kids who wouldn't care about city size and would just love to roam around in a huge city gawking at everything like "Ooh! It's so big!" While tradition can be good, some breaks and changes could serve as nice refreshers, provided they are integrated well.
..Though it would be weird to travel all the way to Nuvema Town, where hardly anyone lives, just to see Professor Juniper after visiting someplace like Hiun City. :/