MMLP and Em Show are classics in my opinion. I think they turns hip hop fans off cuz
1. he's white (this is a real reason for some people)
2. he's too absorbed in himself, people can't really directly relate to those records
3. it was too different from anything else at the time
4. the music isn't really all that timeless (I honestly wouldn't listen to half those beats if it wasn't for Em, but then again I feel the same about Scarface and Nas)
5. cuz he sells so well, he gets mixed up with all the pop acts like Britney and Justin, having bleached hair didn't help things either.
The fact is, Em was spittin classic material on his first 3 albums. Had it been from someone else, they would've been called underground classics at least. Capital Punishment was called a classic, and SSLP was just as good if not slightly behind it.