Why do people care?
So much about IMDb ratings? Just because TDK is 4th on IMDb doesn't than mean it's the 4th greatest movie ever!! People need to realize that guys like Nolan, Fitcher, PTA and more appeal greatly to a teenage audience so of course most 15 year old kids won't know who Tarkovsky, Bergman, Kieslowski, Fellini and many many more are. So it's only natural that they would praise what they know and vote up very good movies like TDK or Fight Club witch is why these types of films rank so highly on IMDb. But it's not like the numbers on IMDb are facts just people's opinions like all "best movies of all time" lists are. Personally I really like the sight and sound top 100 directors picks I would rather listen to a film director than critics or random people but that's just me.
Sorry if my writing is bad English is not my first language:)