I know when you get an up-vote on a question, your reputation score increases of 5, for an answer, it's +10, an accepted answer, it's +15 and finally, you accept an answer is +2 and there's more.
Well, I know very well how the reputation score works since I read this question and answer which is very well explained.
My questions : When you down-vote a question or an answer, why it's only decreasing the reputation by 2 ? Why this doesn't have the opposite cost of an up-vote ?
As an example, if I down-vote a question, instead of -2, it would be -5. For question, -10 instead of -2. For what reasons did they choose this value (-2 for both) about down-voting ?