At least, the tag easter-egg is evil and should be murdered forthwith. Its definition is ambiguous and it doesn't add any value to the questions it's on. A good portion of them are closed as off-topic anyway.
I'll do it myself. Only a few at a time, since there are about 20. When I'm done, I'll accept this answer.
Just because a good portion of the existing uses of the tag are not on-topic, I wouldn't say that the tag itself is 'evil'. I can see many good questions that might use the tag. For example:
I've heard that in Halo 3 there is a picture in the moon. What is it of?
To which there is a single answer, it is (at least in my opinion) on topic, and it does relate to an easter egg.