Perhaps they just don't know any good riddles anymore...
. I guess that you're right though. And yes, the chests in Betrayal at Krondor were pure fun. Hey, I'm sure it would be possible to make a mod for Morrowind (or rather Oblivion) which includes a couple of those chests. This could be combined with some quests...and a nice plot. It's a shame that I *really* don't know any good riddles...