I think the problem is, at least for me anyway is that these have been done to death and once you've seen one, you've seen all. I'd say once you get to the top 10 you basically know the outcome. Top 5 you definately know (Order may vary of course).
Another issue is that people go for what "revolutionized" this or "influenced" that instead of what they actually feel and that's just flat out boring. I remember in the top 65 animation, I forget who, but I mentioned something along the lines of liking Justice League more than Batman: TAS, and that person agreed, but said something like "if it weren't for Batman it wouldn't exist". I can't speak for anybody else, but that killed most of my interest in topics like this.
Toonzone took a shot at doing a "Top ___ videogame thread" and that shuffled off and died, so it could be fatigue of the topic in general.
Mass Effect 1
Halo: Combat Evolved Anniversary