I don't think it's necessary to keep "nominations" from hiding in obscurity. Again, if it's important, someone will notice it and reverse it. If it isn't, then it doesn't matter anyway. This is especially true because we already point out that an article has been deleted when someone actually tries to read that article.
Speedy deletion nominations aren't permanently logged in a central place, only in the edit history. They disappear from the directory as soon as the tag is removed. Have you got any idea how often speedy tags are removed? Just because I don't notice them being removed, doesn't mean it's not important.
Ah, I see what you mean now, you're talking about speedy deletion nominations. Can't these be put on [[Wikipedia:Speedy deletions]] for a central location? I don't really see what this has to do with AfD, anyway.
I'm saying that listing articles on a central page rather than tagging and categorizing them avoid people from removing tags which shouldn't be removed.