When drawing up plots and plans, I personally always forget that players can simply ask for the answers directly once they gain appropriate access/resources. I'm aware that this is a failing on my part and it's pretty much always a bad idea to institute home rules/setting changes purely to accommodate a weak DM.

Having said that, I don't seem to be improving, and I want to provide my players an actual challenge beyond "I buff teh monsterz higher, muhaha!", so I've considered the following change/setting flavor to the worlds I run campaigns in:

1)No easy answers: The deities and other forces of the setting don't like to hand mortals answers in the first place, and are notoriously likely to respond in riddles, and after a delay.
2)General beats specific: When asking questions, one is actually more likely to get a helpful non-evasive response the more general the query is. "What will the weather in this region be like at some point in the next month?" might actually net an inquirer "It's definitely going to rain for three days straight at some point." Whereas "What is the family name of the person most ultimately responsible for the death of the king of <country>?" is almost certainly going to result in a three-part poetic play which answers the question in metaphor.
3)Everybody gets one: Recognizing mortals won't ever stop asking questions, the gods in general have an agreement to answer one direct question with a direct answer of honest intent, per mortal per lifetime.

Item of note that may support/negate these proposed changes: It's already canon in my preferred setting that the deity which once held the domain of omens and prophecy is some time dead, his/her/its domain being held in trust by another until a successor rises.

Obviously, these would seem be heavy-handed and me acting out of bitterness/frustration were I to just drop them into the setting; I'd be discussing any potential changes and the reasons for them with my group rather than just letting them know "this is how the world works now" as the next group of PCs starts.

In particular, I'm hoping/thinking item (3) would blunt any hard feelings at the alteration, and make it an interesting part of the character creation process as well; a question at creation would become, "Have you used your question? If so, what was the question, and what was the answer? (or do you want the DM to tell you what the answer was, muhaha?)"

Any thoughts for/against, or obvious flaws or alternate approaches? (or any handy plot design tips to counter divination?)