Did you notice why it requires 10 reputation? Unfortunately, new users don't often contribute the best content. That particular question has attracted a lot of pretty bad content. The mod who protected it has been around for quite a long time (going on 4 years; he also has the 11th most reputation on the site ATM). I don't think you're in much of a position to judge the wisdom of his decision, even if you happen to have a revolutionary contribution to the question (I don't doubt that you might, FWIW).
If you hang around long enough, you'll see how much work there is to do in just managing the messes others create. New users are somewhat disproportionately responsible for this. Those of us who clean it up are volunteering our time. Please try to appreciate the importance of allocating that time efficiently. Sifting through several non-answers for one proverbial gold nugget is not efficient generally. That's effectively what you'd be asking of the site's users if they unprotected this question just for you.
If you believe what you have to say is important, do stick around and earn your voice on less sensitive topics. Surely there are some easier questions to answer if you can even contribute in a big way to a question that's already been answered (more than) 9 times over two years. If you answer well, you'll probably get your first upvote while your answer is still fresh. Notice that answering other unanswered questions is what the
protected banner itself suggests. This suggestion is there thanks to a recent feature request that was completed (more specifically, thanks to Jon Ericson – send him an upvote!):
"Can we do something more useful when new users land on a protected question?"
If you can't do that, you might get your reputation just about as quickly by finding some posts to edit. Five accepted edits will give you enough to answer, and 25 will give you enough to comment. Again, you might be surprised just how much content out there needs proofreading. Pay your respects to the site and do a little cleanup work with us, and we'll be happy to consider the new content you wish to add. That's how I understand the rep requirement. I don't see anything wrong from this perspective.
Edit: BTW, the association bonus for getting 200 rep on another site won't count toward the rep requirement for answering a protected question, which depends on rep gained specifically on that question's site. As my comments below indicate, this is news to me...Please see this feature-request:
Improve "Protected Question" message with regard to rep gained through Association Bonus