the basis of fashion. as for what constitutes fashion… that’s dependent on how those who are compelling characters and arguers, trendsetters and the regarded establishment in fact feel.
consider it subjective.
a critic who doesn’t like a peice will voice that, in turn that will advertise that fact, it is their own choice, you don’t have to like any of the examples you gave, for instance personally i have little or no regard for kafka, he is however the choice of certain tutors of a certain persuasion (which leads to ideas of indoctrination rather than education within philosophical bounds), and while Villa Savoye may have a place in architectural history personally I find it bland and nondescript.
it’s also worth noting that timeless and great or noteworthy are all different things.
very little is timeless, what can look out at you from the past and be as fresh and pertinent today as it was when it was penned/painted? how pertinent will it be a couple of hundered years from now? no, there is a lot that is linked to it’s era, and ironically the more succesful or great the person behind it the more that it is of it’s time, the greater the chance that it becomes identifiable with a period.
a great person in their own lifetime is more than likely to be the product of self advertising, example of such men are edison, picasso, dali, dunlop, disney, whether the greatness continues is dependent on a number of things, not least of which is how well they got on with reporters and critics.
postumous greatness is a fickle thing, subject to fashion, many artists have gone in and out of fashion, been “rediscovered”, mostly by critics and curators looking to make a name for themselves, after all they are the ones who stand to gain from such the “discovery”, but the same is true for downplaying a popular artist.