Should I have answered it even though no one is going to notice?
Pro Webmasters ranks extremely well on all search engines even the oldest of old questions can get regular views and improving the answers and questions will benefit the community greatly. It's also worth noting that many regular community members browse Pro Webmaster using 'active' and not by newest.
Meaning that even old questions that receive improvements should it be edits or newer answers then that question becomes active and sorted at the top, regularly old questions and improvements receive +1's. I personally 'REALLY' appreciate members improving older questions than newer because it makes our answer to question ratio higher, because let's admit it... no one likes clicking a like of a question only to find that no one has left a response.