You're not looking at it in the grand scheme of things. He has a point. Just looking at the writings during the time classical music was being made you can tell how intricate their thoughts were. This was because sentences had to answer also possible questions because if you were to send a letter to someone, you might not get it back for months or years. Now with the growth of technology and the population, you see things like the internet culture with ttyl, omg, lmao, etc. Along with the technology comes to ablility to create shitty music with ease. I think he's not referring to lyrical hiphop, I think he's referring to songs with a simple rhymic pattern and simplistic lyrics.
Even then, most music (period) from the past few decades have been the same 4/4 time verse chorus verse stuff. There are some exceptions, but that standard stands for most songs.