Above The Rim soundtrack sold 2 million in 94
Murder was the Case soundtrack sold 2 million in 94
Dogg Food sold 2 Million in 95
AEOM sold 5 Million in 96
Makaveli sold 4 Mill in 96
Doggfather sold 2 Mill in 96
Deathrow's "decline" was due to unforeseen circumstances, not a drop off in relevance or oversaturation.

if we're talking sales, then half the commercial albums back then were "classics."
And going by my original theory of pre Dr. Dre and post Dr. Dre....Doggystyle sold 11 million world wide and the Chronic album sold 6 million. By comparison that is still a "decline" post 1994 compared to the sales of the albums you've listed.
I mean is anyone REALLY going to sit here and say that Murder Was the Case is a classic sdtk except for one or two tracks? Same thing with Above the Rim?
Is Dogg Food is a classic album, except for 2 or 3 tracks?
AEOM is a double disk album with slightly more a few good tracks but "classic?"
Makeveli same deal...and Doggfather?
I mean according to your logic "Da Game is To be Sold" by SNoop is a "classic" because it went double platinum...and "No Limit Top Dogg" is a "classic" because it sold 1.5 mill LOL.
Either way, not a single one of those albums are classics...some may have classic tracks, but they are just old ass albums.
I get the feeling that people are just nostalgic about those albums simply because they are just old. Nothing else.