Lyrositor, the KI GPS system was paramount in solving the offline To D'ni expansion, which ended with a definite reward at the end. With the online game there is currently nothing that tangible, but the coordinates have enabled some to make very detailed maps. I would say that being able to make, share and play marker quests is a definite reward.
The 14 marker missions could be looked at as "busy work", but actually can be fun as you try to find all the markers and try to lower your times. Some require "heroic" measures to register the markers. The red and green markers only light up as you get close, and you click inside your KI to register them. The yellow markers in the marker missions (calibration markers) stay visibile but you have to physically pass through them to register them.
Personally, I kept a list of the 14 missions with small notes for each for the general and specific areas the markers were found (Great Stairs, Kahlo Pub, Ferry Terminal, Canyon, Museum, etc.). That makes finding them again more easy.
More practical uses of marker quests have included Minkata guides, identifying hard to get to locations in Ae'gura or in the various ages.
One note, we never have been given free access to the City Proper, only the island called Ae'gura. I'm sure that had been down the line in Cyan's plans.
Have fun!
_________________
<--- Click
"Laugh it up, Chuckles" -- Space Ghost to Rand Miller; MOUL KI #38615, Mulligan KI #37069