Its because you exhausted the pool of good books (Score 5, Insightful)

Imagine a pile of 100 best sci-fi books ever, and a new one is out once every 3 years or so. When you are just getting into sci-fi as a teenager, you can be assured to have a big pile of great sci-fi to read ahead of you.

As you finish it all, it becomes harder and harder to find new good ones, which gives the impression that "today sci-fi is not as good as the years past". Its only the impression, because you wen't thru 50 years best sci-fi in maybe 5-6 years.

Now you have to wait 2-3 years to discover another gem, while before you could have just went to any "best 100 list" and picked any one up.

My recent great finds: The bright of the sky: Entire and the Rose (can't even begin to describe it), Alastair Reynolds Revelation Space universe, Commonwealth Saga + Dreaming Void by Peter Hamilton.

My recent disappointments: Neal Asher. Tried to read Gridlinked, could not even finish.