I don't think increasing the rep loss from downvotes in this way is useful. Basically it comes down to this: downvoted answers are not nearly as hurtful to the site as upvoted answers are helpful to it.
Consider the case where a user posts two answers (to different questions): one correct and one clearly wrong. The wrong one attracts several downvotes; the correct one gets one upvote. Which one is more important: the incorrect one or the correct one?
Since the incorrect one has been downvoted, few people will see it, and those who do will also see that the community has rejected the statements therein. As such, the damage from the incorrect post is essentially eliminated by having a negative score. By contrast, the good answer is useful because it correctly answers a question.
So in the end, the damage caused by a bad answer (assuming it is correctly scored) is less important than the benefits of a good answer. As such, we should care more about good answers than bad ones.
The principal purpose of voting of any kind is to provide a score to the content. Votes give/remove reputation as a form of gratitude/chastisement for the quality of the content. But the quality of the site is what matters most.
And I do not see how reducing reputation more in the case of a heavily downvoted answer helps the quality of the site.
That having been said, the one case where that might be in some way useful goes back to that parenthetical from a few paragraphs back: "assuming it is correctly scored". Because sometimes... answers aren't correctly scored. Answers which are subtly bad often get upvotes by people who don't know what the problem is (and sometimes even afterwards). That is a far more pernicious problem.
But even then, adding more rep-loss in such cases doesn't really solve the problem. If the OP cannot be convinced through comments and downvotes to correct their answer, then the OP probably isn't going to be convinced to do so by increasing how much rep they lose from getting 10 downvotes on a 50 upvoted answer. Even if you make the rep loss exceed the rep gain, they probably won't change it, because at the end of the day, it's still a highly-upvoted answer.