I think the biggest issue you're not really getting is that by striving to release a "classic" album, some artists may compromise their sound to fit into the mold of previous classic albums. Not every hip-hop album needs to sound like Illmatic to be a classic, not every rock album has to sound like Sgt. Pepper's or whatever, not everyone should be trying to sound like Bon Iver just because he released a great record.
There may be some related aspects that take an album into the "classic" level that are common across many, but one I think is definitely necessary is crafting a unique style that is cohesive across an entire album. The issue comes from certain artists striving to repeat the style from a perceived greatness from one album, when they have higher potential going in a different stylistic direction. In this way, by copying the format and tone of a great "classic" album in order to release their own classic, they compromise their style to fit into a mold they don't necessarily match, while also releasing an album that is not as strong as it could have been if they just played towards their strong suits and released what they wanted to without having the pressure of needing a "classic" in their catalog.
Essentially, artists would be better off listening less to what albums fans name as instant classics, and more focusing on what they can do to make the best album in the sound they're going for.