Requiring players to use oracles vs. leaving them as a backup option

[jefgodesky]

Without digging into too much detail, my game could require some fairly intense bouts of creativity, like coming up with riddles.  I realize this is not something I can expect of my players, at least not all the time.  I also love the Oracles that Vincent introduced in IaWA.  My first inclination is to include oracles in my game to solve this problem (so you can randomly generate things like riddles), but leave the option open to use your own.  Am I missing something?  Does allowing a player to choose whether or not they use an oracle break something I'm simply not aware of right now?