On AU (and all other SE sites, I think), you need 10+ reputation to post on a protected question.
Why 10? It's very easy to achieve and you only need one answer upvote. We've seen bad answers get upvoted before.
So, why not something like 50 reputation? It's harder and will ensure higher-quality posts.
Protection isn't a catch all, we don't want it to be. Protection is only there to stop the blatant and obvious, and hopefully make users who would otherwise post non answers in the answer section understand how this site works better. If protection was higher (like 50 reputation) new users wouldn't bother to post an answer. We don't want that. As it already is, I'm sure a lot of them don't.
Essentially protection is to make it just hard enough to stop most non answers, but not so hard that people give up trying to post their answer.
I agree with Seth.
Considering that the goal of protection here is to stop SPAM and fast-way crap, 10 reputation is enough.
Your proposition of 50 rep required is too much and will put new users in a high wall when they could provide useful information on very important questions.
