This is very true, and the reason behind it very misunderstood. It has nothing to do with appreciation, intelligence, or education, much as the elitists want to think otherwise.
English is a very fluid language and changes incredibly rapidly. This makes English literature more difficult to understand as time passes -- on the extreme you can see something like Chaucer's _Cantebury Tales_, which although it is possible to gain some understanding really requires translation for a 21st Century English speaker to understand.