Is there any reason to explore

[Enkidoh]

You get XP for discovering each location.

Sadly not anymore, at least, not in the ARR zones - SE changed it in the 3.2 patch that the map in ARR zones would be automatically completed the first time a player enters that zone instead of having to go around each zone filling in the map. You still get exp for filling in the map for Heavensward zones though. Not that the exp was much but it all added up. A

However the 3.2 patch notes still mention getting the exp bonus for completing the map... but I'm not sure if it's a cumulative total of the exp that the player would have otherwise gained manually completing the map, a token small amount or what, as I completed those maps a long time ago (many years before the 3.2 patch change) so I have no way of verifying this. So take what I said with a grain of salt.