[coldtea]

>So I think there's something basically unfair about the system. If you get donwvotes for posting a question which is considered bad, shouldn't you also receive upvotes for a question which is considered good?

Could also be considered thusly:

Questions that are considered bad, people want to avoid (seeing posted) - so they get downvotes.

Questions that are considered good get upvotes.

As for questions that don't get either, doesn't mean they're good, as you seem to presume. Rather, they're neutral, and thus ignored. People don't really care about encouraging the posting of more of them.