I don't think he dumbed down his lyrics at all. In some ways they are even more complex than before. Its just that now Kanye thinks he can drop 32 bars with 3 mins of beats and be done. Ask yourself when was the last time he spit 3 verses consistenly.
Ye has ONE classic album. College dropout. The others are the same to me, though I prefer his music before 808 & Heartbreaks I still fucks with them all. I like his new flow, just miss his old subject matter.