Style and Great Literature

Often, when listening to someone listing works of great literature, one may notice that almost all the works on the list are somewhat old; almost never is a work written in the last ten years, or even in contemporary, relatively informal English, included.  Why is this?  Did people simply stop writing works of great literature in the early 1990's?  I do not think so.  However, I think that the number of people writing in less formal English increased dramatically, and that society does not at the moment tend to consider works written this way as candidates for great literature.

Even the more recent works of great literature are not written in informal and straightforward styles.  They tend either to be in high style (formal English, typical of the early 1900's) or in a novel style, such as stream-of-consciousness or abstract metaphor.  I think that this discrimination against works written in less formal English is not at all justified; such works can still have great aesthetic merit (in imagery, or even in choice of words) and incredible depth in terms of character development, plot, world-building, insight into psychological states, and in fact all the areas which make great works of older literature great.