Could it be that the magical talent of humans in this era was really inferior to the Dark Age?
That was probably not the real reason. Geresco left a note on the cover of the Book of Eternity. "Knowledge is the most devout faith of a mage!" That sentence was actually not a secret. That famous quote could be found in the library of the Supreme Council and many other libraries of Guilds of Magic.
Almost every mage knew of that quote from Geresco, but those who could truly follow it were few and far between. Hence, it was no exaggeration to say that the mages of the modern era had lost the faith that mages ought to have and the desire for knowledge.