I'm not sure whether it's technically possible to implement.
Idea: allow users to define the "difficulty" of the problem. Each user can vote to determine how hard the problem is, from $1$ to $10$. The difficulty can be measured for:
- Reputation calculation.
- "Hot" question sorting.
About the first point: I have a feeling similar to this: one could easily get a lot of points answering trivial questions, and very few - answering hard ones. While, of course, the motivation should come primarily from the inside, I think it's good to add some reward, even if symbolic. This is also part of the reason why I prefer commenting to answering for easy questions: I don't think I deserve any reward for that. With this, the reputation for such questions will be nerfed, so at least this issue will disappear.
The first point is simple: I would like to see harder (read "more interesting") questions first.
Exact difficulty calculation I suggest is the weighted average of all votes. The weight of each user can be discussed, but I think it can be along the lines of $\log (\max(1, reputation - C))$. We should also add a "bias user" with a fairly large weight and fixed vote.
Reputation calculation: Positive reputation gains should be proportional to difficulty. E.g. when one answers a question with difficulty $1$, they gain $+2$ per upvote, when with difficulty $10$, they gain $+20$ per upvote.