I don't want to turn this into a sales pitch for GW2, but GW2 pretty explicitly rewards you for exploration. Following the quest chain through an area (to the extent that there is one; the chain is slightly orthogonal) only reveals an incomplete picture of the zone. The zone itself explicitly informs you that there are a number of Things Left To Do Here. Collecting all of those is a necessary component to crafting legendary weapons.
So there are a couple levels for exploration: if you don't want to do it, then hurrying through the quest chain gives you lots of XP and you can move on. If you're mildly curious, you can go collect the stuff that interests you, without any real damper on your experience if you decline. If you're gung-ho about exploration for its own sake, there are also plenty of hidden bits and pieces everywhere that aren't necessarily collectibles.
So there are a couple levels for exploration: if you don't want to do it, then hurrying through the quest chain gives you lots of XP and you can move on. If you're mildly curious, you can go collect the stuff that interests you, without any real damper on your experience if you decline. If you're gung-ho about exploration for its own sake, there are also plenty of hidden bits and pieces everywhere that aren't necessarily collectibles.