Why not always use Generics?

Question

I am reading existing posts on Generics at SO. If Generics has so many advantages like Type safety, no overhead of boxing/unboxing and it is fast, why not always use it? Why

Answer 1

Generics makes the code much more reusable, add type safety etc. If you see any good API (Jdk, Scala etc) you will see Generics everywhere. The biggest challenge with Generics is, it's bit tricky to get used to with it and hence many programmer find generics not readable code.

But then here we should fix the real problem (bridging knowledge Gap ) instead of avoiding Generics.