Right, well the way I see it is that there are two ways to approach a work of art
a) Historically, where one considers the context it was made in and the influence it had. This actually has little to do with the work itself, it's just about how it was perceived and what it meants to people at the time.
b) Artistically, where one considers it for itself, independent of its context.
Blade Runner is undoubtely major in the first approach, but I'd argue it's minor in the second approach. I don't doubt many people watching Blade Runner still find it great though, so that's just me. My "wasn't that great to begin with" was a bit of a flippant generalization to the Seinfeld thing, because I think it's not super productive to say "well, you should find it good because they did it first"... I mean by that metric, the Lumière shorts are the greatest movies of all time, they invented the whole thing !