The whole clan could make the trip and that still wouldn't mean they had a good reason for wanting to observe the meeting first hand.
But I personally think there is, due to my opinion of how dangerous a prolonged mage-templar war could be, and the effects it can have to the whole words under the White Chantry, elves included (not to mention that the problem between mages templars.
Plus, there are mages and templars, from what we know of the hinterlands, that went too far and started killing civilians. I don't think It's too far to think some templars might to hunting dalish if they meet some, since they have free mages. So a peaceful solution of the mage-templar war is in the dalish's best interest.
Granted, a dalish can't to much other the spying, but maybe the Keeper wanted first-hand experience of what will happen at the conference. We do know that stories narrated by others tend to exaggerate or change some events

.