The last time I quested in DS was over a year ago, so bear that in mind when reading the following. My master life wizard is currently slogging her way through DS, and I've noticed something: the XP is fairly low for quests, bosses, and just regular NPCs. Now, this could just be me, given that I have been in Azteca and Khrysalis, where finishing a quest often nets you 20-40K plus in experience.
Am I viewing DS XP as low simply because I am accustomed to higher-level worlds, or was DS XP tweaked in the past year or so?
I think it's because you're simply accustomed to higher-level worlds. The exp in Dragonspyre isn't that low, but then again, the last (and only time) I completed Dragonspyre was more than 1 year ago.
Try comparing the average XP you get for completing quests to the XP you need to gain a level. In my experience, both go up at about the same rate for most worlds, Grizzleheim being the main exception with its notoriously poor experience.
The XP from Dragonspyre is pretty high for me, but that is probably because I just got to Dragonspyre, and my level isn't a master level, so maybe it is because of your high level, or you haven't been there in a year.