I came across a question on serverfault today that is about 18 months old. The reason I found it is that a 1 rep user had just added an answer. I didn't notice the date at first, and added my own answer as well. This isn't a huge deal for one question, but what about the general case? Does it make sense that any question over, say, a year (or even just six months) should be automatically protected?
I know technology changes and we want the ability to keep older questions up to date, but remember that protecting a question only locks it for users with a small rep.
What about including views as part of the equation? A question that earns a "Popular Question" badge is probably getting enough views from low rep users to really need protection and enough views from higher rep users to get the edit and new answer attention when needed, but lower view questions maybe either don't need the protection or do need the edit/answer help from anyone who does happen to land at the question.
For context, here is a link to a query that shows actual answers that would have been blocked under this proposal, so we can judge the typical quality. Note that to accurately judge this you have to view them in the context of answers that are already available to the question at the time the answer is added: http://data.stackexchange.com/stackoverflow/q/93288/
And here is a query to show how many questions would be effected:
Notethat this is a naive query: it only checks answer count rather than whether the answer has an upvote, and there's no way right now to know how many of these are already protected. Using the current data set, the result is 114039, or a little less than 1/10th of all questions, and because of the other limitations it's probably even smaller.