hip hop fans are childish and fickle
This is the REAL reason.
Any culture that doesn't respect its history won't last.
Today's hip-hop fan doesn't think the past is relevant enough to matter, and ignorantly tries to downplay the contributions of past greats.
Also, these young kids have followed the 50 Cent model and think that if you're not in the Top 10 on the rap charts, you're irrelevant, which shrinks the artist pool of the culture.
And so, here we are....