Originally posted by Nerevar:

there is not much reason to add more incentive to them when the same wasnt done for other dungeons either. some of which are entirely pointless.

Doesn't need to be much reason. A small good reason is enough. Maybe a rare new gemstone - Safire worth 1000 coins. Isn't that much, but could be enough just because it's there and it's rare.

See, it doesn't have to be that different from earlier when there were rubies lying around.