Final Fantasy is about the journey - the story and the experience. There has not been a single, original Fantasy Fantasy title where the developers allowed for players to have unlimited sprint by design. That they allow you to sprint in a city at all is a miracle, considering they could have forced players to walk. In fact, they would rather add crystals in cities than give players unlimited sprint; that is how distasteful it is to the developers. They would rather move game assets than give players unlimited sprint; the reason you can see the next node is because they want you feel it is a reasonable distance away without feeling the need to run there. It wasn't designed to be an inconvenience for players who farm for hours going from one node to the next, prompting a discussion about unlimited sprint. Someone mentioned that movement speed impacts the whole game and its experience; they're right, which is why unlimited sprint would undoubtedly break that balance.

As for increasing/decreasing the cool down for gatherers - sure, you can suggest they fiddle with that a bit and see how it goes. In the city? Use the crystals - that's why they put them there!