I can see your argument, but the one thing I put down about silent film is that the pictures themselves didn't seem "complete". Leaving out sound is a vital part of a film, and I know a great many foley artists who would weep at your comments. I have never been a huge fan of films made pre-Birth of a Nation. I enjoy watching them from an evolutionary perspective, but it is simply groundwork for what came later, and I still find the films too constricted and many are painfully slow. The twenties are a fascinating period and as the month of July would prove for me, I happen to have a hard on for silent films largely from this period. 

My knowledge of 80's world cinema is abysmal so my opinion on that is going to be limited. I have frequently found though that my favorite films from the decade are often films that get little serious recognition outside of limited "cult" audiences. However as people are starting to appreciate more and more films from this era the tide may be changing. 

My original goal in limiting my choice was to be specific. Saying 1920's world cinema is broad, but saying silent Soviet films from the montage school would fit the original idea behind my choice. However you could just look at my first post as an attempt to glorify all that Hollywood achieved in those early sound years.