I think above is generally a valid concernvalid concern. However some system limitations make it rather slippery to use popularity and historical interest as an ultimate criteria on deciding whether to keep such questions.
Thing is, visual difference between "normal" and historically lockedhistorically locked questions is not really as prominent as it may seem to experienced users. I recall seeing at meta references to examples when inexperienced users didn't notice the differences and thought that these are normal, legitimate questions, "Why can't I ask X when Y exists?""Why can't I ask X when Y exists?"
- Set up an archive for legendary deleted questionsSet up an archive for legendary deleted questions (at MSE)
- Recent Trouble With Popularity
If you take a closer look at this site history described heredescribed here you may find out that it is most likely not so.