The answer to the question I asked was edited by the answerer but I didn't receive any notification. This is a feature that shouldn't be omitted, after-all, the answers to questions are the reason why we are all here.
First: I took a look at the question that you asked and that I assume that you are referring to. An aanswer was given, then you asked for a picture and I would think that you would have expected (or hoped for) the answer to be edited. So I am not sure that I understand how a notification would have benefited much.
Second: That said, I would not oppose if this did become an option that could be selected, but I do not think that this should be implemented as default for everyone. Some thoughts:
This could actually lead to a lot of notifications. It is not unusual to see several answers to a question and have each answer be edited several times.
I don't think that it is too hard to keep an eye on the answers given until one satisfies you. With the questions that I have asked, I usually keep an eye on any updates for sometime after having accepted an answer.
It is already possibly to notify a person by using the @username. So maybe the encouragement should simply be that if an answerer edits an answer after days have past, they should/could use @OP.