Q:
GW2 xp rates and scaling
“In PvE a character’s effective level and attributes are automatically reduced based on level themed sectors within the given zone. For example, a character in the Venlin Vale area of Brisban Wildlands will be lower level than a player in the Koga Ruins area of the same zone. Although skills and equipment (runes and sigils particularly) are retained, zones should still be challenging to play.”
“A scaled down character continues to receive experience and loot that is comparable to what they would receive at their real level, though it is still somewhat less efficient for obtaining experience and items than playing level-appropriate content.”
http://wiki.guildwars2.com/wiki/Dynamic_level_adjustment
You won’t earn as much XP as you would in an appropriately leveled zone, but if will still offer a good chunk of experience. With a higher level character you should be able to blaze through it fairly quickly. You will need to complete them eventually for Map Completion if you ever plan on going for a Legendary weapon. Better to get it out of the way early or the XP will continue to scale down as you gain even more levels.
And depending on your load out of items, it will also be easier, quicker so run off the beaten path and clear out critters for those areas for bonus XP as well.
RIP City of Heroes
Especially now that lower level creatures have had their difficulty reduced because of the trait levels increasing, it’s even easier to kill them for comparable experience.
-Mike O’Brien
Because we can’t be angry about both?